what are research studies called

Please consult the following sources for more information on these types of studies and terminology related to the studies.

• APA Style JARS Supplemental Glossary This webpage provides supplemental information on the terms used in APA Style JARS. This glossary is meant to supplement Chapter 3 of the Publication Manual of the American Psychological Association, Seventh Edition. It is not an exhaustive list of all terms employed in quantitative, qualitative, or mixed methods research, nor does it include all possible definitions for each term; definitions in addition to or different from those reported in this glossary may be found in other sources.
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Understanding Clinical Trials

Clinical research: what is it.

Your doctor may have said that you are eligible for a clinical trial, or you may have seen an ad for a clinical research study. What is clinical research, and is it right for you?

Clinical research is the comprehensive study of the safety and effectiveness of the most promising advances in patient care. Clinical research is different than laboratory research. It involves people who volunteer to help us better understand medicine and health. Lab research generally does not involve people — although it helps us learn which new ideas may help people.

Every drug, device, tool, diagnostic test, technique and technology used in medicine today was once tested in volunteers who took part in clinical research studies.

At Johns Hopkins Medicine, we believe that clinical research is key to improve care for people in our community and around the world. Once you understand more about clinical research, you may appreciate why it’s important to participate — for yourself and the community.

What Are the Types of Clinical Research?

There are two main kinds of clinical research:

Observational Studies

Observational studies are studies that aim to identify and analyze patterns in medical data or in biological samples, such as tissue or blood provided by study participants.

Clinical Trials

Clinical trials, which are also called interventional studies, test the safety and effectiveness of medical interventions — such as medications, procedures and tools — in living people.

Clinical research studies need people of every age, health status, race, gender, ethnicity and cultural background to participate. This will increase the chances that scientists and clinicians will develop treatments and procedures that are likely to be safe and work well in all people. Potential volunteers are carefully screened to ensure that they meet all of the requirements for any study before they begin. Most of the reasons people are not included in studies is because of concerns about safety.

Both healthy people and those with diagnosed medical conditions can take part in clinical research. Participation is always completely voluntary, and participants can leave a study at any time for any reason.

“The only way medical advancements can be made is if people volunteer to participate in clinical research. The research participant is just as necessary as the researcher in this partnership to advance health care.” Liz Martinez, Johns Hopkins Medicine Research Participant Advocate

Types of Research Studies

Within the two main kinds of clinical research, there are many types of studies. They vary based on the study goals, participants and other factors.

Biospecimen studies

Healthy volunteer studies.

 Goals of Clinical Trials

Because every clinical trial is designed to answer one or more medical questions, different trials have different goals. Those goals include:

Treatment trials

Prevention trials, screening trials, phases of a clinical trial.

In general, a new drug needs to go through a series of four types of clinical trials. This helps researchers show that the medication is safe and effective. As a study moves through each phase, researchers learn more about a medication, including its risks and benefits.

Is the medication safe and what is the right dose?   Phase one trials involve small numbers of participants, often normal volunteers.

Does the new medication work and what are the side effects?   Phase two trials test the treatment or procedure on a larger number of participants. These participants usually have the condition or disease that the treatment is intended to remedy.

Is the new medication more effective than existing treatments?  Phase three trials have even more people enrolled. Some may get a placebo (a substance that has no medical effect) or an already approved treatment, so that the new medication can be compared to that treatment.

Is the new medication effective and safe over the long term?   Phase four happens after the treatment or procedure has been approved. Information about patients who are receiving the treatment is gathered and studied to see if any new information is seen when given to a large number of patients.

“Johns Hopkins has a comprehensive system overseeing research that is audited by the FDA and the Association for Accreditation of Human Research Protection Programs to make certain all research participants voluntarily agreed to join a study and their safety was maximized.” Gail Daumit, M.D., M.H.S., Vice Dean for Clinical Investigation, Johns Hopkins University School of Medicine

Is It Safe to Participate in Clinical Research?

There are several steps in place to protect volunteers who take part in clinical research studies. Clinical Research is regulated by the federal government. In addition, the institutional review board (IRB) and Human Subjects Research Protection Program at each study location have many safeguards built in to each study to protect the safety and privacy of participants.

Clinical researchers are required by law to follow the safety rules outlined by each study's protocol. A protocol is a detailed plan of what researchers will do in during the study.

In the U.S., every study site's IRB — which is made up of both medical experts and members of the general public — must approve all clinical research. IRB members also review plans for all clinical studies. And, they make sure that research participants are protected from as much risk as possible.

Earning Your Trust

This was not always the case. Many people of color are wary of joining clinical research because of previous poor treatment of underrepresented minorities throughout the U.S. This includes medical research performed on enslaved people without their consent, or not giving treatment to Black men who participated in the Tuskegee Study of Untreated Syphilis in the Negro Male. Since the 1970s, numerous regulations have been in place to protect the rights of study participants.

Many clinical research studies are also supervised by a data and safety monitoring committee. This is a group made up of experts in the area being studied. These biomedical professionals regularly monitor clinical studies as they progress. If they discover or suspect any problems with a study, they immediately stop the trial. In addition, Johns Hopkins Medicine’s Research Participant Advocacy Group focuses on improving the experience of people who participate in clinical research.

Clinical research participants with concerns about anything related to the study they are taking part in should contact Johns Hopkins Medicine’s IRB or our Research Participant Advocacy Group .

Learn More About Clinical Research at Johns Hopkins Medicine

For information about clinical trial opportunities at Johns Hopkins Medicine, visit our trials site.

Video Clinical Research for a Healthier Tomorrow: A Family Shares Their Story

Clinical Research for a Healthier Tomorrow: A Family Shares Their Story

Module 1: Introduction: What is Research?

Learning Objectives

By the end of this module, you will be able to:

• Explain how the scientific method is used to develop new knowledge
• Describe why it is important to follow a research plan

The Scientific Method consists of observing the world around you and creating a  hypothesis  about relationships in the world. A hypothesis is an informed and educated prediction or explanation about something. Part of the research process involves testing the  hypothesis , and then examining the results of these tests as they relate to both the hypothesis and the world around you. When a researcher forms a hypothesis, this acts like a map through the research study. It tells the researcher which factors are important to study and how they might be related to each other or caused by a  manipulation  that the researcher introduces (e.g. a program, treatment or change in the environment). With this map, the researcher can interpret the information he/she collects and can make sound conclusions about the results.

Research can be done with human beings, animals, plants, other organisms and inorganic matter. When research is done with human beings and animals, it must follow specific rules about the treatment of humans and animals that have been created by the U.S. Federal Government. This ensures that humans and animals are treated with dignity and respect, and that the research causes minimal harm.

No matter what topic is being studied, the value of the research depends on how well it is designed and done. Therefore, one of the most important considerations in doing good research is to follow the design or plan that is developed by an experienced researcher who is called the  Principal Investigator  (PI). The PI is in charge of all aspects of the research and creates what is called a  protocol  (the research plan) that all people doing the research must follow. By doing so, the PI and the public can be sure that the results of the research are real and useful to other scientists.

Module 1: Discussion Questions

• How is a hypothesis like a road map?
• Who is ultimately responsible for the design and conduct of a research study?
• How does following the research protocol contribute to informing public health practices?

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Nih clinical research trials and you.

The NIH Clinical Trials and You website is a resource for people who want to learn more about clinical trials. By expanding the below questions, you can read answers to common questions about taking part in a clinical trial. 

What are clinical trials and why do people participate?

Clinical research is medical research that involves people like you. When you volunteer to take part in clinical research, you help doctors and researchers learn more about disease and improve health care for people in the future. Clinical research includes all research that involves people.  Types of clinical research include:

• Epidemiology, which improves the understanding of a disease by studying patterns, causes, and effects of health and disease in specific groups.
• Behavioral, which improves the understanding of human behavior and how it relates to health and disease.
• Health services, which looks at how people access health care providers and health care services, how much care costs, and what happens to patients as a result of this care.
• Clinical trials, which evaluate the effects of an intervention on health outcomes.

What are clinical trials and why would I want to take part?

Clinical trials are part of clinical research and at the heart of all medical advances. Clinical trials look at new ways to prevent, detect, or treat disease. Clinical trials can study:

• New drugs or new combinations of drugs
• New ways of doing surgery
• New medical devices
• New ways to use existing treatments
• New ways to change behaviors to improve health
• New ways to improve the quality of life for people with acute or chronic illnesses.

The goal of clinical trials is to determine if these treatment, prevention, and behavior approaches are safe and effective. People take part in clinical trials for many reasons. Healthy volunteers say they take part to help others and to contribute to moving science forward. People with an illness or disease also take part to help others, but also to possibly receive the newest treatment and to have added (or extra) care and attention from the clinical trial staff. Clinical trials offer hope for many people and a chance to help researchers find better treatments for others in the future

Why is diversity and inclusion important in clinical trials?

People may experience the same disease differently. It’s essential that clinical trials include people with a variety of lived experiences and living conditions, as well as characteristics like race and ethnicity, age, sex, and sexual orientation, so that all communities benefit from scientific advances.

See Diversity & Inclusion in Clinical Trials for more information.

How does the research process work?

The idea for a clinical trial often starts in the lab. After researchers test new treatments or procedures in the lab and in animals, the most promising treatments are moved into clinical trials. As new treatments move through a series of steps called phases, more information is gained about the treatment, its risks, and its effectiveness.

What are clinical trial protocols?

Clinical trials follow a plan known as a protocol. The protocol is carefully designed to balance the potential benefits and risks to participants, and answer specific research questions. A protocol describes the following:

• The goal of the study
• Who is eligible to take part in the trial
• Protections against risks to participants
• Details about tests, procedures, and treatments
• How long the trial is expected to last
• What information will be gathered

A clinical trial is led by a principal investigator (PI). Members of the research team regularly monitor the participants’ health to determine the study’s safety and effectiveness.

What is an Institutional Review Board?

Most, but not all, clinical trials in the United States are approved and monitored by an Institutional Review Board (IRB) to ensure that the risks are reduced and are outweighed by potential benefits. IRBs are committees that are responsible for reviewing research in order to protect the rights and safety of people who take part in research, both before the research starts and as it proceeds. You should ask the sponsor or research coordinator whether the research you are thinking about joining was reviewed by an IRB.

What is a clinical trial sponsor?

Clinical trial sponsors may be people, institutions, companies, government agencies, or other organizations that are responsible for initiating, managing or financing the clinical trial, but do not conduct the research.

What is informed consent?

Informed consent is the process of providing you with key information about a research study before you decide whether to accept the offer to take part. The process of informed consent continues throughout the study. To help you decide whether to take part, members of the research team explain the details of the study. If you do not understand English, a translator or interpreter may be provided. The research team provides an informed consent document that includes details about the study, such as its purpose, how long it’s expected to last, tests or procedures that will be done as part of the research, and who to contact for further information. The informed consent document also explains risks and potential benefits. You can then decide whether to sign the document. Taking part in a clinical trial is voluntary and you can leave the study at any time.

What are the types of clinical trials?

There are different types of clinical trials.

• Prevention trials look for better ways to prevent a disease in people who have never had the disease or to prevent the disease from returning. Approaches may include medicines, vaccines, or lifestyle changes.
• Screening trials test new ways for detecting diseases or health conditions.
• Diagnostic trials study or compare tests or procedures for diagnosing a particular disease or condition.
• Treatment trials test new treatments, new combinations of drugs, or new approaches to surgery or radiation therapy.
• Behavioral trials evaluate or compare ways to promote behavioral changes designed to improve health.
• Quality of life trials (or supportive care trials) explore and measure ways to improve the comfort and quality of life of people with conditions or illnesses.

What are the phases of clinical trials?

Clinical trials are conducted in a series of steps called “phases.” Each phase has a different purpose and helps researchers answer different questions.

• Phase I trials : Researchers test a drug or treatment in a small group of people (20–80) for the first time. The purpose is to study the drug or treatment to learn about safety and identify side effects.
• Phase II trials : The new drug or treatment is given to a larger group of people (100–300) to determine its effectiveness and to further study its safety.
• Phase III trials : The new drug or treatment is given to large groups of people (1,000–3,000) to confirm its effectiveness, monitor side effects, compare it with standard or similar treatments, and collect information that will allow the new drug or treatment to be used safely.
• Phase IV trials : After a drug is approved by the FDA and made available to the public, researchers track its safety in the general population, seeking more information about a drug or treatment’s benefits, and optimal use.

What do the terms placebo, randomization, and blinded mean in clinical trials?

In clinical trials that compare a new product or therapy with another that already exists, researchers try to determine if the new one is as good, or better than, the existing one. In some studies, you may be assigned to receive a placebo (an inactive product that resembles the test product, but without its treatment value).

Comparing a new product with a placebo can be the fastest and most reliable way to show the new product’s effectiveness. However, placebos are not used if you would be put at risk — particularly in the study of treatments for serious illnesses — by not having effective therapy. You will be told if placebos are used in the study before entering a trial.

Randomization is the process by which treatments are assigned to participants by chance rather than by choice. This is done to avoid any bias in assigning volunteers to get one treatment or another. The effects of each treatment are compared at specific points during a trial. If one treatment is found superior, the trial is stopped so that the most volunteers receive the more beneficial treatment.  This video helps explain randomization for all clinical trials .

" Blinded " (or " masked ") studies are designed to prevent members of the research team and study participants from influencing the results. Blinding allows the collection of scientifically accurate data. In single-blind (" single-masked ") studies, you are not told what is being given, but the research team knows. In a double-blind study, neither you nor the research team are told what you are given; only the pharmacist knows. Members of the research team are not told which participants are receiving which treatment, in order to reduce bias. If medically necessary, however, it is always possible to find out which treatment you are receiving.

Who takes part in clinical trials?

Many different types of people take part in clinical trials. Some are healthy, while others may have illnesses. Research procedures with healthy volunteers are designed to develop new knowledge, not to provide direct benefit to those taking part. Healthy volunteers have always played an important role in research.

Healthy volunteers are needed for several reasons. When developing a new technique, such as a blood test or imaging device, healthy volunteers help define the limits of "normal." These volunteers are the baseline against which patient groups are compared and are often matched to patients on factors such as age, gender, or family relationship. They receive the same tests, procedures, or drugs the patient group receives. Researchers learn about the disease process by comparing the patient group to the healthy volunteers.

Factors like how much of your time is needed, discomfort you may feel, or risk involved depends on the trial. While some require minimal amounts of time and effort, other studies may require a major commitment of your time and effort, and may involve some discomfort. The research procedure(s) may also carry some risk. The informed consent process for healthy volunteers includes a detailed discussion of the study's procedures and tests and their risks.

A patient volunteer has a known health problem and takes part in research to better understand, diagnose, or treat that disease or condition. Research with a patient volunteer helps develop new knowledge. Depending on the stage of knowledge about the disease or condition, these procedures may or may not benefit the study participants.

Patients may volunteer for studies similar to those in which healthy volunteers take part. These studies involve drugs, devices, or treatments designed to prevent,or treat disease. Although these studies may provide direct benefit to patient volunteers, the main aim is to prove, by scientific means, the effects and limitations of the experimental treatment. Therefore, some patient groups may serve as a baseline for comparison by not taking the test drug, or by receiving test doses of the drug large enough only to show that it is present, but not at a level that can treat the condition.

Researchers follow clinical trials guidelines when deciding who can participate, in a study. These guidelines are called Inclusion/Exclusion Criteria . Factors that allow you to take part in a clinical trial are called "inclusion criteria." Those that exclude or prevent participation are "exclusion criteria." These criteria are based on factors such as age, gender, the type and stage of a disease, treatment history, and other medical conditions. Before joining a clinical trial, you must provide information that allows the research team to determine whether or not you can take part in the study safely. Some research studies seek participants with illnesses or conditions to be studied in the clinical trial, while others need healthy volunteers. Inclusion and exclusion criteria are not used to reject people personally. Instead, the criteria are used to identify appropriate participants and keep them safe, and to help ensure that researchers can find new information they need.

What do I need to know if I am thinking about taking part in a clinical trial?

Risks and potential benefits

Clinical trials may involve risk, as can routine medical care and the activities of daily living. When weighing the risks of research, you can think about these important factors:

• The possible harms that could result from taking part in the study
• The level of harm
• The chance of any harm occurring

Most clinical trials pose the risk of minor discomfort, which lasts only a short time. However, some study participants experience complications that require medical attention. In rare cases, participants have been seriously injured or have died of complications resulting from their participation in trials of experimental treatments. The specific risks associated with a research protocol are described in detail in the informed consent document, which participants are asked to consider and sign before participating in research. Also, a member of the research team will explain the study and answer any questions about the study. Before deciding to participate, carefully consider risks and possible benefits.

Potential benefits

Well-designed and well-executed clinical trials provide the best approach for you to:

• Help others by contributing to knowledge about new treatments or procedures.
• Gain access to new research treatments before they are widely available.
• Receive regular and careful medical attention from a research team that includes doctors and other health professionals.

Risks to taking part in clinical trials include the following:

• There may be unpleasant, serious, or even life-threatening effects of experimental treatment.
• The study may require more time and attention than standard treatment would, including visits to the study site, more blood tests, more procedures, hospital stays, or complex dosage schedules.

What questions should I ask if offered a clinical trial?

If you are thinking about taking part in a clinical trial, you should feel free to ask any questions or bring up any issues concerning the trial at any time. The following suggestions may give you some ideas as you think about your own questions.

• What is the purpose of the study?
• Why do researchers think the approach may be effective?
• Who will fund the study?
• Who has reviewed and approved the study?
• How are study results and safety of participants being monitored?
• How long will the study last?
• What will my responsibilities be if I take part?
• Who will tell me about the results of the study and how will I be informed?

Risks and possible benefits

• What are my possible short-term benefits?
• What are my possible long-term benefits?
• What are my short-term risks, and side effects?
• What are my long-term risks?
• What other options are available?
• How do the risks and possible benefits of this trial compare with those options?

Participation and care

• What kinds of therapies, procedures and/or tests will I have during the trial?
• Will they hurt, and if so, for how long?
• How do the tests in the study compare with those I would have outside of the trial?
• Will I be able to take my regular medications while taking part in the clinical trial?
• Where will I have my medical care?
• Who will be in charge of my care?

Personal issues

• How could being in this study affect my daily life?
• Can I talk to other people in the study?

Cost issues

• Will I have to pay for any part of the trial such as tests or the study drug?
• If so, what will the charges likely be?
• What is my health insurance likely to cover?
• Who can help answer any questions from my insurance company or health plan?
• Will there be any travel or child care costs that I need to consider while I am in the trial?

Tips for asking your doctor about trials

• Consider taking a family member or friend along for support and for help in asking questions or recording answers.
• Plan what to ask — but don't hesitate to ask any new questions.
• Write down questions in advance to remember them all.
• Write down the answers so that they’re available when needed.
• Ask about bringing a tape recorder to make a taped record of what's said (even if you write down answers).

This information courtesy of Cancer.gov.

How is my safety protected?

Ethical guidelines

The goal of clinical research is to develop knowledge that improves human health or increases understanding of human biology. People who take part in clinical research make it possible for this to occur. The path to finding out if a new drug is safe or effective is to test it on patients in clinical trials. The purpose of ethical guidelines is both to protect patients and healthy volunteers, and to preserve the integrity of the science.

Informed consent

Informed consent is the process of learning the key facts about a clinical trial before deciding whether to participate. The process of providing information to participants continues throughout the study. To help you decide whether to take part, members of the research team explain the study. The research team provides an informed consent document, which includes such details about the study as its purpose, duration, required procedures, and who to contact for various purposes. The informed consent document also explains risks and potential benefits.

If you decide to enroll in the trial, you will need to sign the informed consent document. You are free to withdraw from the study at any time.

Most, but not all, clinical trials in the United States are approved and monitored by an Institutional Review Board (IRB) to ensure that the risks are minimal when compared with potential benefits. An IRB is an independent committee that consists of physicians, statisticians, and members of the community who ensure that clinical trials are ethical and that the rights of participants are protected. You should ask the sponsor or research coordinator whether the research you are considering participating in was reviewed by an IRB.

Further reading

For more information about research protections, see:

• Office of Human Research Protection
• Children's Assent to Clinical Trial Participation

For more information on participants’ privacy and confidentiality, see:

• HIPAA Privacy Rule
• The Food and Drug Administration, FDA’s Drug Review Process: Ensuring Drugs Are Safe and Effective

For more information about research protections, see: About Research Participation

What happens after a clinical trial is completed?

After a clinical trial is completed, the researchers carefully examine information collected during the study before making decisions about the meaning of the findings and about the need for further testing. After a phase I or II trial, the researchers decide whether to move on to the next phase or to stop testing the treatment or procedure because it was unsafe or not effective. When a phase III trial is completed, the researchers examine the information and decide whether the results have medical importance.

Results from clinical trials are often published in peer-reviewed scientific journals. Peer review is a process by which experts review the report before it is published to ensure that the analysis and conclusions are sound. If the results are particularly important, they may be featured in the news, and discussed at scientific meetings and by patient advocacy groups before or after they are published in a scientific journal. Once a new approach has been proven safe and effective in a clinical trial, it may become a new standard of medical practice.

Ask the research team members if the study results have been or will be published. Published study results are also available by searching for the study's official name or Protocol ID number in the National Library of Medicine's PubMed® database .

How does clinical research make a difference to me and my family?

Only through clinical research can we gain insights and answers about the safety and effectiveness of treatments and procedures. Groundbreaking scientific advances in the present and the past were possible only because of participation of volunteers, both healthy and those with an illness, in clinical research. Clinical research requires complex and rigorous testing in collaboration with communities that are affected by the disease. As research opens new doors to finding ways to diagnose, prevent, treat, or cure disease and disability, clinical trial participation is essential to help us find the answers.

This page last reviewed on October 3, 2022

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Methodology

Research Methods | Definitions, Types, Examples

Research methods are specific procedures for collecting and analyzing data. Developing your research methods is an integral part of your research design . When planning your methods, there are two key decisions you will make.

First, decide how you will collect data . Your methods depend on what type of data you need to answer your research question :

• Qualitative vs. quantitative : Will your data take the form of words or numbers?
• Primary vs. secondary : Will you collect original data yourself, or will you use data that has already been collected by someone else?
• Descriptive vs. experimental : Will you take measurements of something as it is, or will you perform an experiment?

Second, decide how you will analyze the data .

• For quantitative data, you can use statistical analysis methods to test relationships between variables.
• For qualitative data, you can use methods such as thematic analysis to interpret patterns and meanings in the data.

Table of contents

Methods for collecting data, examples of data collection methods, methods for analyzing data, examples of data analysis methods, other interesting articles, frequently asked questions about research methods.

Data is the information that you collect for the purposes of answering your research question . The type of data you need depends on the aims of your research.

Qualitative vs. quantitative data

Your choice of qualitative or quantitative data collection depends on the type of knowledge you want to develop.

For questions about ideas, experiences and meanings, or to study something that can’t be described numerically, collect qualitative data .

If you want to develop a more mechanistic understanding of a topic, or your research involves hypothesis testing , collect quantitative data .

You can also take a mixed methods approach , where you use both qualitative and quantitative research methods.

Primary vs. secondary research

Primary research is any original data that you collect yourself for the purposes of answering your research question (e.g. through surveys , observations and experiments ). Secondary research is data that has already been collected by other researchers (e.g. in a government census or previous scientific studies).

If you are exploring a novel research question, you’ll probably need to collect primary data . But if you want to synthesize existing knowledge, analyze historical trends, or identify patterns on a large scale, secondary data might be a better choice.

Descriptive vs. experimental data

In descriptive research , you collect data about your study subject without intervening. The validity of your research will depend on your sampling method .

In experimental research , you systematically intervene in a process and measure the outcome. The validity of your research will depend on your experimental design .

To conduct an experiment, you need to be able to vary your independent variable , precisely measure your dependent variable, and control for confounding variables . If it’s practically and ethically possible, this method is the best choice for answering questions about cause and effect.

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Your data analysis methods will depend on the type of data you collect and how you prepare it for analysis.

Data can often be analyzed both quantitatively and qualitatively. For example, survey responses could be analyzed qualitatively by studying the meanings of responses or quantitatively by studying the frequencies of responses.

Qualitative analysis methods

Qualitative analysis is used to understand words, ideas, and experiences. You can use it to interpret data that was collected:

• From open-ended surveys and interviews , literature reviews , case studies , ethnographies , and other sources that use text rather than numbers.
• Using non-probability sampling methods .

Qualitative analysis tends to be quite flexible and relies on the researcher’s judgement, so you have to reflect carefully on your choices and assumptions and be careful to avoid research bias .

Quantitative analysis methods

Quantitative analysis uses numbers and statistics to understand frequencies, averages and correlations (in descriptive studies) or cause-and-effect relationships (in experiments).

You can use quantitative analysis to interpret data that was collected either:

• During an experiment .
• Using probability sampling methods .

Because the data is collected and analyzed in a statistically valid way, the results of quantitative analysis can be easily standardized and shared among researchers.

If you want to know more about statistics , methodology , or research bias , make sure to check out some of our other articles with explanations and examples.

• Chi square test of independence
• Statistical power
• Descriptive statistics
• Degrees of freedom
• Pearson correlation
• Null hypothesis
• Double-blind study
• Case-control study
• Research ethics
• Data collection
• Hypothesis testing
• Structured interviews

Research bias

• Hawthorne effect
• Unconscious bias
• Recall bias
• Halo effect
• Self-serving bias
• Information bias

Quantitative research deals with numbers and statistics, while qualitative research deals with words and meanings.

Quantitative methods allow you to systematically measure variables and test hypotheses . Qualitative methods allow you to explore concepts and experiences in more detail.

In mixed methods research , you use both qualitative and quantitative data collection and analysis methods to answer your research question .

A sample is a subset of individuals from a larger population . Sampling means selecting the group that you will actually collect data from in your research. For example, if you are researching the opinions of students in your university, you could survey a sample of 100 students.

In statistics, sampling allows you to test a hypothesis about the characteristics of a population.

The research methods you use depend on the type of data you need to answer your research question .

• If you want to measure something or test a hypothesis , use quantitative methods . If you want to explore ideas, thoughts and meanings, use qualitative methods .
• If you want to analyze a large amount of readily-available data, use secondary data. If you want data specific to your purposes with control over how it is generated, collect primary data.
• If you want to establish cause-and-effect relationships between variables , use experimental methods. If you want to understand the characteristics of a research subject, use descriptive methods.

Methodology refers to the overarching strategy and rationale of your research project . It involves studying the methods used in your field and the theories or principles behind them, in order to develop an approach that matches your objectives.

Methods are the specific tools and procedures you use to collect and analyze data (for example, experiments, surveys , and statistical tests ).

In shorter scientific papers, where the aim is to report the findings of a specific study, you might simply describe what you did in a methods section .

In a longer or more complex research project, such as a thesis or dissertation , you will probably include a methodology section , where you explain your approach to answering the research questions and cite relevant sources to support your choice of methods.

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• Explanatory Research | Definition, Guide, & Examples
• Exploratory Research | Definition, Guide, & Examples
• External Validity | Definition, Types, Threats & Examples
• Extraneous Variables | Examples, Types & Controls
• Guide to Experimental Design | Overview, Steps, & Examples
• How Do You Incorporate an Interview into a Dissertation? | Tips
• How to Do Thematic Analysis | Step-by-Step Guide & Examples
• How to Write a Literature Review | Guide, Examples, & Templates
• How to Write a Strong Hypothesis | Steps & Examples
• Inclusion and Exclusion Criteria | Examples & Definition
• Independent vs. Dependent Variables | Definition & Examples
• Inductive Reasoning | Types, Examples, Explanation
• Inductive vs. Deductive Research Approach | Steps & Examples
• Internal Validity in Research | Definition, Threats, & Examples
• Internal vs. External Validity | Understanding Differences & Threats
• Longitudinal Study | Definition, Approaches & Examples
• Mediator vs. Moderator Variables | Differences & Examples
• Mixed Methods Research | Definition, Guide & Examples
• Multistage Sampling | Introductory Guide & Examples
• Naturalistic Observation | Definition, Guide & Examples
• Operationalization | A Guide with Examples, Pros & Cons
• Population vs. Sample | Definitions, Differences & Examples
• Primary Research | Definition, Types, & Examples
• Qualitative vs. Quantitative Research | Differences, Examples & Methods
• Quasi-Experimental Design | Definition, Types & Examples
• Questionnaire Design | Methods, Question Types & Examples
• Random Assignment in Experiments | Introduction & Examples
• Random vs. Systematic Error | Definition & Examples
• Reliability vs. Validity in Research | Difference, Types and Examples
• Reproducibility vs Replicability | Difference & Examples
• Reproducibility vs. Replicability | Difference & Examples
• Sampling Methods | Types, Techniques & Examples
• Semi-Structured Interview | Definition, Guide & Examples
• Simple Random Sampling | Definition, Steps & Examples
• Single, Double, & Triple Blind Study | Definition & Examples
• Stratified Sampling | Definition, Guide & Examples
• Structured Interview | Definition, Guide & Examples
• Survey Research | Definition, Examples & Methods
• Systematic Review | Definition, Example, & Guide
• Systematic Sampling | A Step-by-Step Guide with Examples
• Textual Analysis | Guide, 3 Approaches & Examples
• The 4 Types of Reliability in Research | Definitions & Examples
• The 4 Types of Validity in Research | Definitions & Examples
• Transcribing an Interview | 5 Steps & Transcription Software
• Triangulation in Research | Guide, Types, Examples
• Types of Interviews in Research | Guide & Examples
• Types of Research Designs Compared | Guide & Examples
• Types of Variables in Research & Statistics | Examples
• Unstructured Interview | Definition, Guide & Examples
• What Is a Case Study? | Definition, Examples & Methods
• What Is a Case-Control Study? | Definition & Examples
• What Is a Cohort Study? | Definition & Examples
• What Is a Conceptual Framework? | Tips & Examples
• What Is a Controlled Experiment? | Definitions & Examples
• What Is a Double-Barreled Question?
• What Is a Focus Group? | Step-by-Step Guide & Examples
• What Is a Likert Scale? | Guide & Examples
• What Is a Prospective Cohort Study? | Definition & Examples
• What Is a Retrospective Cohort Study? | Definition & Examples
• What Is Action Research? | Definition & Examples
• What Is an Observational Study? | Guide & Examples
• What Is Concurrent Validity? | Definition & Examples
• What Is Content Validity? | Definition & Examples
• What Is Convenience Sampling? | Definition & Examples
• What Is Convergent Validity? | Definition & Examples
• What Is Criterion Validity? | Definition & Examples
• What Is Data Cleansing? | Definition, Guide & Examples
• What Is Deductive Reasoning? | Explanation & Examples
• What Is Discriminant Validity? | Definition & Example
• What Is Ecological Validity? | Definition & Examples
• What Is Ethnography? | Definition, Guide & Examples
• What Is Face Validity? | Guide, Definition & Examples
• What Is Non-Probability Sampling? | Types & Examples
• What Is Participant Observation? | Definition & Examples
• What Is Peer Review? | Types & Examples
• What Is Predictive Validity? | Examples & Definition
• What Is Probability Sampling? | Types & Examples
• What Is Purposive Sampling? | Definition & Examples
• What Is Qualitative Observation? | Definition & Examples
• What Is Qualitative Research? | Methods & Examples
• What Is Quantitative Observation? | Definition & Examples
• What Is Quantitative Research? | Definition, Uses & Methods

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Information for Research Subjects

Learn about becoming a research participant at the University of Rochester

True to the University of Rochester’s Mission Statement, ‘Learn, Discover, Heal, Create—and Make the World Ever Better’, research has been a long-standing tradition at the University of Rochester . Our researchers are among the nation’s leaders across a wide range of fields, including medicine, human behavior, education, politics, optics and economics.

Find an open research study

Faqs: participating in research.

Participating in research can be a fun and exciting way to give back to your community, but it doesn’t necessarily come without risk. Becoming a research participant is an important decision that should be taken seriously.

Background and overview

Research studies are done to discover new information or to answer a question about how we learn, behave, and function. Some studies might involve simple tasks like completing a survey, being observed among a group of people, or participating in a group discussion. Other studies, sometimes called clinical trials, involve more risky procedures like testing a new drug or medical device.

Each research study has its own set of criteria to determine who can participate. This depends on the research question being asked and may include restrictions based on age, behaviors, health status, or other traits.

Deciding to participate

Research is designed to benefit society. This might include learning how to live healthier lives, how to better treat conditions or diseases, why we do the things we do, or how we learn and develop. And while there are several reasons why people choose to participate in research, most people participate based on the possibility of helping themselves or others.

It’s important to understand that you may not directly benefit from participating in research. In fact, with a lot of research, you will not receive any benefit. For some types of research however, there may be a possibility that you could receive benefit, but there is no guarantee.

Most studies involve some risk, though the risks can range from very small to very serious. Some examples of risks include:

• side effects or reactions to experimental drugs, treatments, or procedures
• feeling anxious or uncomfortable
• breach in confidentiality or invasion of privacy.

Side effects or other risks you might experience may be temporary or go away with treatment, but in rare cases they may be permanent, cause disability, or be life threatening. There may also be risks in participating that we don’t know about.

To start, you will be given information about the study so that you can make an informed decision about whether or not to participate. You will also be given an opportunity to ask questions about the study. This process is called informed consent . Before you can start the study, you need to agree to participate (i.e., consent). Participation is always voluntary.

Once you provide consent, the specific procedures or activities you’ll be asked to complete can vary widely and depend on what is being studied. Regardless, all the activities you will be asked to complete will be described during the consent process.

Before you agree to be in the study, make sure you have a solid understanding of the following:

• the voluntary nature of the study
• why the study is being done
• who is doing the study
• the procedures, activities, tests, or treatments involved (including how long they will take, how often they have to be completed, and whether there are any other treatment options available rather than being in the study)
• potential risks, discomforts, or side effects
• potential benefits to participating, if any
• how your privacy will be protected
• how long your participation will last
• what will happen if you are injured while participating
• the costs to you, if any
• what to do if you change your mind about participating
• whom to contact with questions, concerns, or problems

Each study is different, so time requirements will vary. Some may require very little of your time, perhaps only 5–10 minutes, while others may require multiple visits over an extended period of time, sometimes up to several years. Your time commitment for a particular study will be described during the consent process.

informed consent

Informed consent is the process of telling interested individuals what is involved in taking part in a specific research study. Typically, this includes:

• reviewing written information
• giving the potential volunteer time to review this information while considering participation (taking it home to review with friends or family, if desired)
• discussing the information verbally
• answering any questions

Once all of the information is provided to you and your questions are answered, you will then be asked to decide whether or not to take part in the study.

All decisions are voluntary, and you must provide your agreement (i.e., consent) before any study activities can begin. Usually, this involves signing a consent form. Although, for some studies, verbally agreeing to participate may be sufficient.

Once you provide consent to be in the study, you will continue to receive important information about your participation throughout the study.

It’s important to understand what is involved in taking part in a research study and to carefully consider what that means for you. Research can pose risks to your health, safety, and welfare, so it’s important to understand exactly what those risks are.

It’s also important to understand that taking part in research is voluntary. You make the decision about whether or not to participate, and if you agree to take part, you can always change your mind later.

State law determines who can provide consent. In New York State, only individuals 18 years of age and older can provide consent. Minors, based on their age and ability, are usually asked for their agreement to participate in research, but their parent or legal guardian must also provide their permission to participate. Other special considerations are also made when a minor is a ward of the state or adults are unable to make decisions for themselves.

If you have questions about who can or cannot provide consent, be sure to ask the study team.

The following key points are most important about informed consent:

• Being in a study is voluntary—it is your choice.
• If you join a study, you can change your mind and stop at any time.
• If you have questions about anything that is not clear to you, you can ask them at any point of time before, during, or after the study.
• If you feel you need more time or information to make an informed decision about whether or not to take part in the study, do not hesitate to ask for it.

Subject Protections

Research studies involving humans must be approved and monitored by an Institutional Review Board (IRB). An IRB is a committee of individuals responsible for reviewing research to ensure adequate protections are in place to protect the people who take part.

For each study reviewed, the IRB checks to see that:

• there is a good reason to conduct the study
• the risks related to participating are the least possible
• the risks related to participating are reasonable given the knowledge that will be gained from conducting the study
• the plan for selecting subjects to participate is fair
• subjects will be provided enough information about the study

Protecting the information you provide to researchers is a high priority, particularly if you provide health-related or sensitive information.

As part of the IRB approval process described above, all researchers must provide a plan to adequately protect the information they plan to collect in order for the study to be approved. This might include assigning a code to the information collected instead of using your name or other identifiable information and storing the information in a secure manner.

You are free to withdraw from a research study at any time, for any reason. Your relationship with the hospital, clinic, academic institution, or employer will not be affected and you will not lose any benefits to which you are entitled.

Note that in some cases, a researcher may decide to end your participation in the study early. This may happen if the study is no longer in your best interest, if you can no longer complete study activities, or if the study ends early for some other reason.

Additional participant resources

Downloadable information.

• Participating in Research Overview
• Informed Consent

External resources

• About Research Participation (Department of Health & Human Service)
• Children & Clinical Studies (National Heart, Lung & Blood Institute)
• Clinical Research Trials and You (National Institutes of Health)

University research studies

• Search UR Health Research
• Join the UR Health Research Volunteer Registry to be contacted for future studies
• Follow UR Health Research on Facebook
• CenterWatch Clinical Trials Search
• ClinicalTrials.gov
• National Institutes of Health List of Registries
• ResearchMatch

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Report an issue, concern, or complaint

If you have participated in University of Rochester research and would like to report an issue, concern or complaint about the research you, or a family member, has participated in, please do so via our feedback form.

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What Are Cancer Research Studies?

What is cancer research and why is it important.

Research is the key to progress against cancer and is a complex process involving professionals from many fields. It is also thanks to the participation of people with cancer, cancer survivors, and healthy volunteers that any breakthroughs go on to improve treatment and care for those who need it.

Cancer research studies may lead to discoveries such as new drugs to treat cancer, new therapies to make symptoms less severe, or lifestyle changes to reduce the chances of getting cancer.

Cancer research may also address big picture questions like why cancer is more prevalent in certain populations or how doctors can make existing cancer detection tools more effective in health care settings.

These discoveries can help people with cancer and their caregivers live fuller lives.

Who should join cancer research studies?

When you choose to participate in a research study, you become a partner in scientific discovery. Your generous contribution can make a world of difference for people like you.

As scientists continue to conduct cancer research, anyone can consider joining a research study. The best research includes everyone, and everyone includes you.

Your unique experience with cancer is incredibly valuable and may help current and future generations lead healthier lives.

When more people of all different races, ethnicities, ages, genders, abilities, and backgrounds participate, more people benefit.

It is important for scientists to capture the full genetic diversity of human populations so that the lessons learned are applicable to everyone.

What are the types of cancer research studies?

See below for definitions on the four major types of research and their subtypes:

• basic research
• quality of life/supportive care
• natural history
• longitudinal
• population-based
• epidemiological research
• translational research

Basic Research

Basic cancer research studies explore the very laws of nature. Scientists learn how cancer cells grow and divide, for example, by growing and testing bacteria , viruses , fungi , animal cells, and human cells in a lab. Scientists also study, for example, the genes that make up tumors in mice and rats in the lab. These experiments help build the foundation for further discovery.

Why Participate in a Clinical Trial?

Get information on how to evaluate a clinical trial and what questions to ask.

Clinical Research

Clinical research involves the study of cancer in people. These cancer research studies are further broken down into two types: clinical trials and observational studies .

• Treatment trials test how safe and useful a new treatment or way of using existing treatments is for people with cancer. Test treatments may include drugs, approaches to surgery or radiation therapy , or combinations of treatments.
• Prevention trials are for people who do not have cancer but are at a high risk for developing cancer or for cancer coming back. Prevention clinical trials target lifestyle changes (doing something) or focus on certain nutrients or medicines (adding something).
• Screening trials test how effective screening tests are for healthy people. The goal of these trials is to discover screening tools or methods that reduce deaths from cancer by finding it earlier.
• Quality-of-life/supportive care tests aim to help people with cancer, as well as their family and loved ones, cope with side effects like pain, nutrition problems, nausea and vomiting , sleeping problems, and depression . These trials may involve drugs or activities like therapy and exercising.  

Find Observational Studies

View a studies that are looking for people now.

• Natural history studies look at certain conditions in people with cancer or people who are at a high risk of developing cancer. Researchers often collect information about a person and their family medical history , as well as blood, saliva, and tumor samples. For example, a biomarker test may be used to get a genetic profile of a person’s cancer tissue. This may reveal how certain tumors change over the course of treatment .
• Longitudinal studies gather data on people or groups of people over time, often to see the result of a habit, treatment, or change. For example, two groups of people may be identified as those who smoke and those who do not. These two groups are compared over time to see whether one group is more likely to develop cancer than the other group.
• Population-based studies explore the causes of cancer, cancer trends, and factors that affect cancer care in specific populations. For example, a population-based study may explore the causes of a high cancer rate in a regional Native American population.

Epidemiological Research

Epidemiological research is the study of the patterns, causes, and effects of cancer in a group of people of a certain background. This research encompasses both observational population-based studies but also includes clinical epidemiological studies where the relationship between a population’s risk factors and treatments are tested.

Translational Research

Translational research is when cancer research moves across research disciplines, from basic lab research into clinical settings, and from clinical settings into everyday care. In turn, findings from clinical studies and population-based studies can inform basic cancer research. For example, data from the genetic profile of a tumor during an observational study may help scientists develop a clinical trial to test which drugs to prescribe to cancer patients with specific tumor genes.

Monica Bertagnolli, Director, NIH; former director, NCI; cancer survivor

Participation in Cancer Research Matters

I am so happy to have the opportunity to acknowledge the courage and generosity of an estimated 494,018 women who agreed to participate in randomized clinical trials with results reported between 1971 and 2018.

Their contributions showed that mammography can detect cancer at an early stage, that mastectomies and axillary lymph node dissections are not always necessary, that chemotherapy can benefit some people with early estrogen receptor–positive, progesterone receptor–positive, HER2-negative breast cancer but is not needed for all, and that hormonal therapy can prevent disease recurrence.

For just the key studies that produced these results, it took the strength and commitment of almost 500,000 women. I am the direct beneficiary of their contributions, and I am profoundly grateful.

The true number of brave souls contributing to this reduction in breast cancer mortality over the past 30 years? Many millions. These are our heroes.

— From NCI Director’s Remarks by then-NCI Director Monica M. Bertagnolli, M.D., at the American Society of Clinical Oncology Annual Meeting, June 3, 2023

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Types of Research Studies

Epidemiology studies.

Epidemiology is the study of the patterns and causes of disease in people.

The goal of epidemiology studies is to give information that helps support or disprove an idea about a possible link between an exposure (such as alcohol use) and an outcome (such as breast cancer) in people.

The 2 main types of epidemiology studies are:

• Observational studies ( prospective cohort or case-control )

Randomized controlled trials

Though they have the same goal, observational studies and randomized controlled trials differ in:

• The way they are conducted
• The strengths of the conclusions they reach

Observational studies

In observational studies, the people in the study live their daily lives as they choose. They exercise when they want, eat what they like and take the medicines their doctors prescribe. They report these activities to researchers.

There are 2 types of observational studies:

Prospective cohort studies

Case-control studies.

A prospective cohort study follows a large group of people forward in time.

Some people will have a certain exposure (such as alcohol use) and others will not.

Researchers compare the different groups (for example, they might compare heavy drinkers, moderate drinkers, light drinkers and non-drinkers) to see which group is more likely to develop an outcome (such as breast cancer).

In a case-control study, researchers identify 2 groups: cases and controls.

• Cases are people who already have an outcome (such as breast cancer).
• Controls are people who do not have the outcome.

The researchers compare the 2 groups to see if any exposure (such as alcohol use) was more common in the history of one group compared to the other.

In randomized controlled trials (randomized clinical trials), researchers divide people into groups to compare different treatments or other interventions.

These studies are called randomized controlled trials because people are randomly assigned (as if by coin toss) to a certain treatment or behavior.

For example, in a randomized trial of a new drug therapy, half the people might be randomly assigned to a new drug and the other half to the standard treatment.

In a randomized controlled trial on exercise and breast cancer risk, half the participants might be randomly assigned to walk 10 minutes a day and the other half to walk 2 hours a day. The researchers would then see which group was more likely to develop breast cancer, those who walked 10 minutes a day or those who walked 2 hours a day.

Many behaviors, such as smoking or heavy alcohol drinking, can’t be tested in this way because it isn’t ethical to assign people to a behavior known to be harmful. In these cases, researchers must use observational studies.

Patient series

A patient series is a doctor’s observations of a group of patients who are given a certain treatment.

There is no comparison group in a patient series. All the patients are given a certain treatment and the outcomes of these patients are studied.

With no comparison group, it’s hard to draw firm conclusions about the effectiveness of a treatment.

For example, if 10 women with breast cancer are given a new treatment, and 2 of them respond, how do we know if the new treatment is better than standard treatment?

If we had a comparison group of 10 women with breast cancer who got standard treatment, we could compare their outcomes to those of the 10 women on the new treatment. If no women in the comparison group responded to standard treatment, then the 2 women who responded to the new treatment would represent a success of the new treatment. If, however, 2 of the 10 women in the standard treatment group also responded, then the new treatment is no better than the standard.

The lack of a comparison group makes it hard to draw conclusions from a patient series. However, data from a patient series can help form hypotheses that can be tested in other types of studies.

Strengths and weaknesses of different types of research studies

When reviewing scientific evidence, it’s helpful to understand the strengths and weaknesses of different types of research studies.

Case-control studies have some strengths:

• They are easy and fairly inexpensive to conduct.
• They are a good way for researchers to study rare diseases. If a disease is rare, you would need to follow a very large group of people forward in time to have many cases of the disease develop.
• They are a good way for researchers to study diseases that take a long time to develop. If a disease takes a long time to develop, you would have to follow a group of people for many years for cases of the disease to develop.

Case-control studies look at past exposures of people who already have a disease. This causes some concerns:

• It can be hard for people to remember details about the past, especially when it comes to things like diet.
• Memories can be biased (or influenced) because the information is gathered after an event, such as the diagnosis of breast cancer.
• When it comes to sensitive topics (such as abortion), the cases (the people with the disease) may be much more likely to give complete information about their history than the controls (the people without the disease). Such differences in reporting bias study results.

For these reasons, the accuracy of the results of case-control studies can be questionable.

Cohort studies

Prospective cohort studies avoid many of the problems of case-control studies because they gather information from people over time and before the events being studied happen.

However, compared to case-control studies, they are expensive to conduct.

Nested case-control studies

A nested case-control study is a case-control study within a prospective cohort study.

Nested case-control studies use the design of a case-control study. However, they use data gathered as part of a cohort study, so they are less prone to bias than standard case-control studies.

All things being equal, the strength of nested case-control data falls somewhere between that of standard case-control studies and cohort studies.

Randomized controlled trials are considered the gold standard for studying certain exposures, such as breast cancer treatment. Similar to cohort studies, they follow people over time and are expensive to do.

Because people in a randomized trial are randomly assigned to an intervention (such as a new chemotherapy drug) or standard treatment, these studies are more likely to show the true link between an intervention and a health outcome (such as survival).

Learn more about randomized clinical trials , including the types of clinical trials, benefits, and possible drawbacks.

Overall study quality

The overall quality of a study is important. For example, the results from a well-designed case-control study can be more reliable than those from a poorly-designed randomized trial.

Finding more information on research study design

If you’re interested in learning more about research study design, a basic epidemiology textbook from your local library may be a good place to start. The National Cancer Institute also has information on epidemiology studies and randomized controlled trials.

Animal studies

Animal studies add to our understanding of how and why some factors cause cancer in people.

However, there are many differences between animals and people, so it makes it hard to translate findings directly from one to the other.

Animal studies are also designed differently. They often look at exposures in larger doses and for shorter periods of time than are suitable for people.

While animal studies can lay the groundwork for research in people, we need human studies to draw conclusions for people.

All data presented within this section of the website come from studies done with people.

Joining a research study

Research is ongoing to improve all areas of breast cancer, from prevention to treatment.

Whether you’re newly diagnosed, finished breast cancer treatment many years ago, or even if you’ve never had breast cancer, there may be breast cancer research studies you can join.

If you have breast cancer, BreastCancerTrials.org in collaboration with Susan G. Komen® offers a custom matching service that can help find a studies that fit your needs. You can also visit the National Institutes of Health’s website to find a breast cancer treatment study.

If you’re interested in being part of other studies, talk with your health care provider. Your provider may know of studies in your area looking for volunteers.

Learn more about joining a research study .

Learn more about clinical trials .

Learn what Komen is doing to help people find and participate in clinical trials .

Updated 12/16/20

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Study designs: Part 1 – An overview and classification

Priya ranganathan.

Department of Anaesthesiology, Tata Memorial Centre, Mumbai, Maharashtra, India

Rakesh Aggarwal

1 Department of Gastroenterology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India

There are several types of research study designs, each with its inherent strengths and flaws. The study design used to answer a particular research question depends on the nature of the question and the availability of resources. In this article, which is the first part of a series on “study designs,” we provide an overview of research study designs and their classification. The subsequent articles will focus on individual designs.

INTRODUCTION

Research study design is a framework, or the set of methods and procedures used to collect and analyze data on variables specified in a particular research problem.

Research study designs are of many types, each with its advantages and limitations. The type of study design used to answer a particular research question is determined by the nature of question, the goal of research, and the availability of resources. Since the design of a study can affect the validity of its results, it is important to understand the different types of study designs and their strengths and limitations.

There are some terms that are used frequently while classifying study designs which are described in the following sections.

A variable represents a measurable attribute that varies across study units, for example, individual participants in a study, or at times even when measured in an individual person over time. Some examples of variables include age, sex, weight, height, health status, alive/dead, diseased/healthy, annual income, smoking yes/no, and treated/untreated.

Exposure (or intervention) and outcome variables

A large proportion of research studies assess the relationship between two variables. Here, the question is whether one variable is associated with or responsible for change in the value of the other variable. Exposure (or intervention) refers to the risk factor whose effect is being studied. It is also referred to as the independent or the predictor variable. The outcome (or predicted or dependent) variable develops as a consequence of the exposure (or intervention). Typically, the term “exposure” is used when the “causative” variable is naturally determined (as in observational studies – examples include age, sex, smoking, and educational status), and the term “intervention” is preferred where the researcher assigns some or all participants to receive a particular treatment for the purpose of the study (experimental studies – e.g., administration of a drug). If a drug had been started in some individuals but not in the others, before the study started, this counts as exposure, and not as intervention – since the drug was not started specifically for the study.

Observational versus interventional (or experimental) studies

Observational studies are those where the researcher is documenting a naturally occurring relationship between the exposure and the outcome that he/she is studying. The researcher does not do any active intervention in any individual, and the exposure has already been decided naturally or by some other factor. For example, looking at the incidence of lung cancer in smokers versus nonsmokers, or comparing the antenatal dietary habits of mothers with normal and low-birth babies. In these studies, the investigator did not play any role in determining the smoking or dietary habit in individuals.

For an exposure to determine the outcome, it must precede the latter. Any variable that occurs simultaneously with or following the outcome cannot be causative, and hence is not considered as an “exposure.”

Observational studies can be either descriptive (nonanalytical) or analytical (inferential) – this is discussed later in this article.

Interventional studies are experiments where the researcher actively performs an intervention in some or all members of a group of participants. This intervention could take many forms – for example, administration of a drug or vaccine, performance of a diagnostic or therapeutic procedure, and introduction of an educational tool. For example, a study could randomly assign persons to receive aspirin or placebo for a specific duration and assess the effect on the risk of developing cerebrovascular events.

Descriptive versus analytical studies

Descriptive (or nonanalytical) studies, as the name suggests, merely try to describe the data on one or more characteristics of a group of individuals. These do not try to answer questions or establish relationships between variables. Examples of descriptive studies include case reports, case series, and cross-sectional surveys (please note that cross-sectional surveys may be analytical studies as well – this will be discussed in the next article in this series). Examples of descriptive studies include a survey of dietary habits among pregnant women or a case series of patients with an unusual reaction to a drug.

Analytical studies attempt to test a hypothesis and establish causal relationships between variables. In these studies, the researcher assesses the effect of an exposure (or intervention) on an outcome. As described earlier, analytical studies can be observational (if the exposure is naturally determined) or interventional (if the researcher actively administers the intervention).

Directionality of study designs

Based on the direction of inquiry, study designs may be classified as forward-direction or backward-direction. In forward-direction studies, the researcher starts with determining the exposure to a risk factor and then assesses whether the outcome occurs at a future time point. This design is known as a cohort study. For example, a researcher can follow a group of smokers and a group of nonsmokers to determine the incidence of lung cancer in each. In backward-direction studies, the researcher begins by determining whether the outcome is present (cases vs. noncases [also called controls]) and then traces the presence of prior exposure to a risk factor. These are known as case–control studies. For example, a researcher identifies a group of normal-weight babies and a group of low-birth weight babies and then asks the mothers about their dietary habits during the index pregnancy.

Prospective versus retrospective study designs

The terms “prospective” and “retrospective” refer to the timing of the research in relation to the development of the outcome. In retrospective studies, the outcome of interest has already occurred (or not occurred – e.g., in controls) in each individual by the time s/he is enrolled, and the data are collected either from records or by asking participants to recall exposures. There is no follow-up of participants. By contrast, in prospective studies, the outcome (and sometimes even the exposure or intervention) has not occurred when the study starts and participants are followed up over a period of time to determine the occurrence of outcomes. Typically, most cohort studies are prospective studies (though there may be retrospective cohorts), whereas case–control studies are retrospective studies. An interventional study has to be, by definition, a prospective study since the investigator determines the exposure for each study participant and then follows them to observe outcomes.

The terms “prospective” versus “retrospective” studies can be confusing. Let us think of an investigator who starts a case–control study. To him/her, the process of enrolling cases and controls over a period of several months appears prospective. Hence, the use of these terms is best avoided. Or, at the very least, one must be clear that the terms relate to work flow for each individual study participant, and not to the study as a whole.

Classification of study designs

Figure 1 depicts a simple classification of research study designs. The Centre for Evidence-based Medicine has put forward a useful three-point algorithm which can help determine the design of a research study from its methods section:[ 1 ]

Classification of research study designs

• Does the study describe the characteristics of a sample or does it attempt to analyze (or draw inferences about) the relationship between two variables? – If no, then it is a descriptive study, and if yes, it is an analytical (inferential) study
• If analytical, did the investigator determine the exposure? – If no, it is an observational study, and if yes, it is an experimental study
• If observational, when was the outcome determined? – at the start of the study (case–control study), at the end of a period of follow-up (cohort study), or simultaneously (cross sectional).

In the next few pieces in the series, we will discuss various study designs in greater detail.

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Nursing Research: What It Is and Why It Matters

When people think about medical research, they often think about cutting-edge surgical procedures and revolutionary new medications. As important as those advancements are, another type of research is just as vital: nursing research.

This type of research informs and improves nursing practice. In many cases, it’s focused on improving patient care. Experienced nurses who have advanced nursing degrees and training in research design typically conduct this research.

Nurse research can explore any number of topics, from symptomology to patient diet. However, no matter the focus of a research project, nurse research can improve health care in an impressive number of ways. As experts in their field, nurse researchers can pursue a wide range of unique career advancement opportunities .

Why Nursing Research Matters: Examples of Research in Action

Research drives innovation in every industry. Given that nurses are on the front line of the health care industry, the research they do can be particularly impactful for patient outcomes. 

It Can Improve Patients’ Quality of Life

Patients diagnosed with life-threatening chronic diseases often undergo intense treatments with sometimes debilitating side effects. Nursing research is vital to helping such patients maintain a high quality of life.

For example, a 2018 study led by a nurse scientist explored why cancer patients undergoing chemotherapy frequently experience severe nausea. While the physical toll of chemotherapy contributes to nausea, the study found that patients who have factors such as children to take care of, high psychological stress, and trouble performing day-to-day tasks are often much more likely to experience nausea.

By identifying the root causes of nausea and which patients are more likely to experience it, this research allows health care professionals to develop evidence-based care practices . This can include prescribing anti-nausea medications and connecting patients to mental health professionals.

It’s Central to Making Health Care More Equitabl

A Gallup survey reports that about 38% of Americans put off seeking medical treatment due to costs. Unfortunately, cost is only one factor that prevents people from seeking treatment. Many Americans don’t live close to medical providers that can meet their needs, aren’t educated about health, or encounter discrimination.

As complex as this issue is, the National Institute of Nursing Research (NINR) asserts that the country’s nurse researchers can lead the charge in tackling it. In its strategic plan for 2022 to 2026, the institute highlights the following:

• Nursing has long been one of the most trusted professions in the country.
• Nurses often interact with patients, patients’ families, and communities more frequently than other health care professionals.
• The care that nurses provide must often take environmental and social factors into account.

These traits put nurses in the position to not only research health inequity but also put their research to work in their organizations. To help make that happen, NINR often funds nurse-led research projects focused on equity and social determinants of health. With that kind of backing, the field may become more transformative than ever.

It Can Strengthen the Health Care Workforce

While nursing research can be used to improve patient care, it can also be leveraged to solve issues health care professionals face daily. Research about the state of the health care workforce during the COVID-19 pandemic is a perfect illustration.

In 2022, a team of nurse researchers published a report called Nursing Crisis: Challenges and Opportunities for Our Profession After COVID-19 in the International Journal of Nursing Practice . In it, the authors provided concrete statistics about the following:

• Mental and physical health issues many nurses encountered
• Effects of increased workloads and decreased nurse-to-patient ratios
• How many nurses were planning to leave the profession altogether

As nurses themselves, the authors also offer actionable, evidence-based solutions to these issues, such as streamlining patient documentation systems and implementing employee wellness programs.

However, this type of research isn’t just important to solving workforce issues stemming from specific emergencies, such as the COVID-19 pandemic. By publishing quantifiable data about the challenges they face, nurse researchers empower other nurses and professional nursing organizations to advocate for themselves. This can help employers enact effective policies, support their nursing staff, and draw more talented people into the profession.

Career Opportunities in Nursing Research

Nurse researchers can work in any number of administrative, direct care, and academic roles. However, because nurse research often requires clinical care and data analysis skills, jobs in this field typically require an advanced degree, such as a Master of Science in Nursing (MSN).

While many more nurse research career opportunities exist, here are four career paths nurses with research experience and advanced degrees can explore.

Nurse Researcher

Nurse researchers identify issues related to nursing practice, collect data about them, and conduct research projects designed to inform practice and policy. While they often work in academic medical centers and universities, they can work for any type of health care provider as well as health care advocacy agencies.

In addition to conducting research, these professionals typically provide direct patient care. Many also write papers for peer-reviewed journals and make presentations about their work at conferences.

Clinical Research Nurse

Despite having a similar title to nurse researchers, clinical research nurses have slightly different responsibilities. These professionals are usually in charge of providing care to patients participating in medical research projects, including clinical trials and nursing research initiatives. They also typically collect data about patient progress, coordinate care between different team members, and contribute to academic papers.

Occupational Health Nurse

Also referred to as environmental health nurses, occupational health nurses serve specific communities, such as professionals in a particular industry or people who live in a particular area. They often educate their communities about relevant health risks, advocate for stronger health and safety regulations, and run wellness programs.

To carry out their duties, occupational and environmental health nurses must typically research health trends about the people they serve, including living and working conditions that put them at risk for illness or injury. They can work for private companies and government agencies.

Nurse Educator

Nurse educators prepare new nurses to enter the workforce or train experienced nurses in more advanced techniques. This can include teaching classes and providing on-the-job training. They often work for colleges, universities, and large health care providers.

While their duties don’t always include research, nurse educators must keep up with the health care industry’s needs and new patient care practices. This is so they can provide relevant education themselves and help their organizations design up-to-date curricula.

Make Nursing Research a Part of Your Journey

Conducting and implementing nurse research is a collaborative effort. It takes a team of informed leaders, skilled analysts, and creative educators to create effective, evidence-based policies. Those interested in pursuing nurse research should consider The University of Tulsa’s online MSN program , which can prepare you to fill any one of those roles and more.

All of TU’s MSN students take classes on research and evidence-based practices. However, the program’s specialty tracks allow students to take their studies in multiple research-oriented directions. For instance, if you’re interested in collecting and interpreting clinical data, you can choose the Informatics and Analysis track. If you have a passion for public health policy, the Public Health and Global Vision track includes classes on population health and epidemiology.

Delivered in a flexible online format, this program can be a great option for working nurses and nontraditional students alike. To find out more, read about TU’s admission policies and request more information today.

Recommended Readings

A Nurse Educator’s Role in the Future of Nursing

How Global Health Nursing Supports Population Health

What Can You Do With an MSN?

Gallup, “Record High in U.S. Put Off Medical Care Due to Cost in 2022”

International Journal of Nursing Practice, “Nursing Crisis: Challenges and Opportunities for Our Profession After COVID‐19”

Journal of Pain Symptom Management , “Risk Factors Associated With Chemotherapy-Induced Nausea in the Week Prior to the Next Cycle and Impact of Nausea on Quality of Life Outcomes”

Mayo Clinic, Nursing

National Institute of Nursing Research, Scientific Strategy: NINR’s Research Framework

National Institute of Nursing Research, The National Institute of Nursing Research 2022-2026 Strategic Plan

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Submission and Review

Submitting applications, irb applications.

All IRB applications are completed and submitted electronically through our online system OneAegis (IRBManager).  OneAegis can be accessed through single-sign-on (SSO), or by clicking here .

The IRB application form is configured to support multiple types of submissions.

Initiate a new application for:

• New human subjects research projects
• Establishing a data repository or recruitment registry – a standalone recruitment registry or data/specimen repository. Registries and repositories require standalone protocols and cannot be embedded within an application for a larger project.
• A Preliminary IRB Determination – for a funded project that lacks definite plans for the involvement of human subjects because time is needed after funds are awarded to develop the final protocol and related study materials. A Preliminary IRB Determination is often requested to meet Just-In-Time requirements.
• Request to rely on an external (non-ISU) IRB — for studies involving collaboration between researchers at ISU and another institution, where the other Institution’s IRB will assume oversight responsibilities for both sites. If Iowa State will serve as reviewing IRB, please complete the relevant sections within a regular “Human Subjects Research Project” form.

An amendment is needed for the following actions associated with approved research:

• Modifications (guidance for non-exempt and exempt research )
• Continuing Review ( guidance )
• Closing the study ( guidance )

See OneAegis (IRBManager) How-To’s for instructional guidance for initiating various types of forms.

Exempt Review Wizard

The Exempt Review Wizard is an online form in the IRB’s online system (OneAegis, formerly IRBManager). The Wizard automates certification of exemption for certain types of research.  Please review the following document’s information about eligibility, using the Wizard, and the automated review process.

Step-by-step instructions are available here .

Reporting Adverse Events or Unanticipated Problems

Serious adverse events or unanticipated problems involving risk to participants or others are reported through a form in OneAegis (IRBManager).  See related IRB guidance for detailed reporting requirements and timelines.

Incidents that pose an immediate risk of serious harm to participants or others must be reported immediately to [email protected] or by phone ( staff directory ).

OneAegis (formerly called IRBManager)

OneAegis is the electronic system for IRB application submission and management of IRB-related study records. OneAegis was formerly called IRBManager—the system itself has not changed.

OneAegis supports an online IRB application and review process with conditioned questions, automated CITI training verification for study personnel, electronic signatures and routing, and email notifications for actions needed. It also allows for collaboration between researchers when completing the IRB application, as well as collaboration with the IRB office during IRB review. All IRB-related study materials and records are contained within the application and the online study record.

Entering Study Personnel

ISU-Affiliated personnel:  Personnel are identified by their ISU email address. If an ISU-affiliated individual is not recognized when their email address is entered, they must log into OneAegis using their ISU credentials one time to establish themselves as a contact in the system. After this one-time log in, personnel can be added to the IRB application.

We strongly advise having all study personnel log into IRBManager before you complete the IRB application.

Non-ISU-Affiliated:  Persons who do not have an ISU email address can be added using the form “Add Non-ISU Contact” in the Key Personnel section of the IRB application.

Signatures and Routing

IRB applications must be signed by the PI and Supervising Investigator (if applicable).  Applications for new studies must also be reviewed and signed by the Chair of the Department overseeing the research.  Individuals are notified by email when an IRB application needs review and signature.  Signing the form involves entering username and password.  After the form is signed, it will automatically route to the next stage in the submission or review process.

During the review process, IRB staff may send the form back with questions or revisions.  Those who need to take action (e.g., submitter, PI, etc.) are notified via email.

OneAegis FAQ’s

The IRB application shows that my CITI training is “Missing.”  What do I do?

OneAegis verifies CITI training completion by connecting with CITI databases overnight each day.  Successful verification requires that the individual’s CITI account documents their affiliation with ISU and lists their ISU email address as the Primary Email Address in CITI.

If you have taken the training and your training is listed as “Missing” in the IRB application, please do the following:

• Check your CITI account and ensure you are affiliated with ISU and your ISU email address is listed as your primary email address.
• Check OneAegis the next day (after an overnight update).

If after the training still shows as “Missing” after both of the above steps are completed, please contact the IRB office ([email protected]).

The system does not find an ISU-affiliated individual when I enter their email address. What do I do?

If you see a message indicating contact not found after entering an ISU email address, that means the individual is not established as a contact in OneAegis.

All personnel must log into OneAegis using their ISU credentials (email address and password) one time to establish themselves as a contact in the system before they can be added to IRB applications. Individuals will be automatically established as a contact after logging into the system once—there are no additional forms to complete for ISU-affiliated persons.

We strongly advise having all study personnel log into IRBManager once, if they have not done so already, before you complete the IRB application.

OneAegis How-To’s

Review process & timelines.

IRB applications undergo a pre-review process to ensure that all materials and information needed for review are included and to determine the level of review necessary for the study (i.e., exempt review, expedited review, or review by the full committee). The terms exempt and expedited refer to categories of research that do not require review by the full committee. At ISU, expedited reviews are conducted by IRB Chair(s) or designated IRB members.  Exempt reviews are conducted by qualified IRB staff.

Following IRB approval, the approved application, the IRB-stamped supporting documents, and the IRB approval letter are available to the PI and Supervising Investigator (SI) in OneAegis (IRBManager). PIs/SIs should read the approval letter carefully as it contains important information. Also, the IRB-stamped informed consent document should be used when enrolling study participants.

Review timelines depend on three primary factors:

• Review volume – IRB review load is typically highest mid-semester.
• Application quality – clear, complete, and internally consistent applications require much less communication between the PI and IRB staff, and therefore, less review time.
• Project complexity – complex, novel, or risky research typically requires more review time.  In some instances, consultation with outside experts, legal counsel, or other campus departments is needed. Those processes take extra time.

PIs are advised to submit their applications well in advance of the proposed start date or the continuing review date of the study. Although a review often takes less time than shown in the table below, it’s wise to allow for the longer time frame, especially during peak periods such as the middle of fall and spring semesters.

IRB Meeting Schedule/Application Submission Deadlines

IRB meetings are normally held on the first and third Tuesdays of each month, including over the summer.*  Completed applications must be submitted two full weeks in advance of the meeting.  The two-week period is needed to prepare applications for the board and ensure IRB members have sufficient time for review.

Please note:  The application due date applies only to applications to be reviewed by the convened IRB.  Applications for exempt research or research that will be reviewed by a designated IRB member (i.e., “expedited review”) do not have submission deadlines; instead, these applications are placed in a queue for review in the order received.

*Changes in this schedule sometimes occur due to members’ absences, particularly during the summer and breaks or near University holidays.

IRB Approval Criteria

Federal regulations established the following criteria that must be satisfied for the IRB to approve non-exempt research.  IRB application questions are designed to obtain the information reviewers need to assess whether project plans align with these criteria.

Risks to subjects are minimized – sound scientific design, no unnecessary procedures, adequate plans to prevent harm (when possible), researchers are qualified, etc.

Risks are reasonable in relation to anticipated benefits of the research – in other words, there must be adequate scientific justification for exposing research participants to any risks associated with the study.

Subject selection is equitable – participant selection should be justified by the research question(s); not solely due to ease of access (particularly if they may be vulnerable).

The research plan includes adequate provisions to protect the privacy of subjects and to maintain confidentiality of the data collected – the IRB considers both privacy and confidentiality at all parts of the study (recruitment, during data collection, security of the data, when reporting results or sharing data, etc.).

Informed consent will be obtained from each participant prior to their inclusion in the study and in accordance with regulatory requirements , unless waived by the IRB .

Informed consent will be documented (by handwritten or electronic signature), unless this requirement is waived by the IRB.  If the documentation requirement is waived, the IRB may require written information to be provided to research participants.

When appropriate, additional safeguards are in place to protect the rights and welfare of subjects who may be vulnerable to coercion or undue influence (children, educationally or economically disadvantaged, individuals with impaired decision-making capacity, prisoners, students or employees—in some cases).

When appropriate (i.e., clinical trials, high risk research, etc.), the research plan includes adequate provisions for monitoring the data collected to ensure the safety of subjects.