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Research 101 Glossary of Terms

January 4, 2022
9 minutes
Evidation Highlights

Doctors and scientists use a lot of language that can be hard for the average person to understand. This "jargon" helps them communicate effectively with one another, but it can make learning about research difficult.

When we talk about health research, we sometimes need to use these terms to be as specific and transparent as possible.

So, to help, we've put together this list of common research terms and their definitions.

Common Health Research Terms

You can refer back to this page anytime you need to, and we'll update it to reflect new topics we post about.

Aggregate data

Data from a group of individuals that is combined into a summary format, for example, in tables or graphs. When data is aggregated (combined), individuals cannot be identified by their data. 

Clinical Research

Clinical research is a type of health science which aims to produce knowledge that is valuable for understanding human disease, preventing and treating illness, and promoting health.  

Coded study data

Data from a study which does not contain personally identifiable information (PII), for example, name, address, date of birth, social security number, etc. The PII is replaced by a code (usually a string of random letters and numbers) so no one can know who the participant is just from looking at the dataset. The participant’s corresponding personal information is kept separate to protect their identity as much as possible.


A group of individuals who share a common characteristic or group of characteristics who are observed in a study. For example, the feature they may have in common could be a health diagnosis or a treatment assignment.

Sometimes, this term can also be used to refer to a group that a study participant is assigned to, such as a “study branch”, "study group", or “study arm”. 


  • In a study on diabetes, researchers may observe a set of traits patients diagnosed with diabetes who are on insulin (cohort 1) and who are not on insulin (cohort 2)
  • In a study on how social media affects people of different ages, researchers might  observe symptoms in people age 10-15 (cohort 1), 16-20 (cohort 2), and 21-25 (cohort 3)


Confidentiality refers to how an individual’s personal data is protected by people or groups granted permission to process it. It refers to how a person’s information is treated once it has been shared. Maintaining confidentiality is an important way to protect privacy and build trust.

Control group

The control group in a randomized controlled trial does not receive an “experimental treatment”, or the treatment that is being tested. Instead, they may receive no treatment, or another treatment that gets compared to the treatment being tested. The purpose of the control group is to compare research results between the group that receives the treatment and the group that doesn’t. 

For example, in a study that wants to learn whether a pain medication is helpful, one group would get the pain medication and the other group wouldn’t. The group that does not receive the pain medication is known as the control group. The data from these two groups could then be compared to learn more about whether the pain medication (the treatment or drug) is helpful.


A process used to remove any personally identifying information (or PII) from data collected during a study. This is used to protect the identity of participants in a research study.

De-identified data

Data that is not linked to any personally identifying information (or PII), which means that it cannot be linked back to a specific person. 

Decentralized trial

A research trial that is not conducted at a physical location or “site” (also referred to sometimes as a “siteless” trial). Instead of having participants come to a location to complete study activities, they are able to participate from where they are (i.e. online, using home care, telemedicine visits, etc.)

Eligibility criteria

Criteria for who can or cannot participate in a research study, as defined by the researchers. These criteria must be met by all participants. Eligibility criteria are put in place to make sure that the researchers are able to get meaningful data to answer the study’s research questions, and/or protect people who may experience negative effects from a study. Eligibility criteria are different for any study.

For example, a study researching a birth control pill in females may exclude males. That same study may exclude females with heart conditions for their safety, if the birth control being tested is known to cause heart problems.

Eligibility screening

Questions or activities used to determine (or “screen”) if a person is eligible to participate in a study. This often occurs in the form of a survey, but could include other activities such as interviews or medical assessments.


The process of entering into a research study or trial. This can include a variety of steps, including agreeing to participate in a study by signing the informed consent form.

Exclusion criteria

Any criteria that would make a person ineligible to participate in a study. Exclusion criteria are created by the researchers to make sure the study results are meaningful and to protect potential participants from study activities that could be harmful to them. 

For example, a study may exclude participants who take a blood pressure medication, if there is reason to believe that people taking that type of medication could be harmed by the study. 

Good Clinical Practice

Good Clinical Practice (GCP) is an international guide for how to conduct ethical and good quality research. GCP applies to every aspect of a study, from start to finish. The purpose of this guide is to protect the rights and safety of study participants, as well as ensure the integrity and quality of study data.

Health research

Research that aims to learn about human health. This type of research can help us learn about, prevent, and treat health conditions. Also sometimes referred to as clinical research. 


HIPAA stands for the Health Insurance Portability and Accountability Act of 1996. It is a U.S. federal law that created guidelines to protect patients' PHI (personal health information). For more details on how HIPAA applies to research, click here

Inclusion criteria

Criteria that a person must meet to be eligible to participate in a study. 

For example, a study that is researching a blood pressure medication may require individuals to have high blood pressure. 

Informed consent

A process by which a person voluntarily confirms that they are willing to participate in a particular study. During this process, the person is given detailed information about the study so that they can make an informed decision about whether they want to participate. If a person decides to participate in a study, their consent is documented on an Informed Consent Form.

Informed Consent Form (ICF)

A form used to explain and document a person’s willingness to participate in a specific study. The form provides any important information a person needs to be able to decide whether participating in the study is right for them. For example, the form will include information on the purpose of the study, who is conducting the study, and any risks.

Interventional Research

Studies which are designed to understand the effects of treatment or preventive measures on a condition. This can also be described as “experimental research.” 

For example, a researcher may want to understand if an anxiety medication can also be used to treat chronic pain. In such a study, the researcher may give the anxiety medication to individuals with chronic pain, to see if the medication affects them. 

Institutional Review Board (IRB)

A group which independently reviews any research involving people. This group is made up of at least five members with different scientific and non-scientific backgrounds (for example, researchers, doctors, nurses, scientists, psychologists, patients, etc.)  The role of the IRB is to ensure that participants' rights and welfare are protected and that studies are carried out in an ethical manner.

Observational Research

Studies which are designed to observe what happens to a group of participants. Unlike interventional research, observational research does not try to introduce a treatment or product, but instead observes how participants behave naturally.

For example, a researcher may want to observe how depression affects the average number of steps a person walks per day. 


A person who enrolls (or takes part) in a research study after signing an informed consent form and completing any other study-required enrollment activities.

Person-Generated Health Data

Health-related data that is created, recorded, or gathered by individuals (or by family members or caregivers). Sources of PGHD include wearable devices or phones, electronic surveys, apps, or any other interactions with technology that generate personal data about health. 

Personally identifiable information (PII)

Personally identifiable information (PII) is any form of sensitive data that can be used to identify a person (for example, name or social security number). A study that collects PII is required to protect that data.


Privacy refers to a person’s right to limit access or processing of their personal information by other people or groups. This can include controlling what, how much, and when personal information is shared with others

Principal Investigator

The person(s) who leads and takes overall responsibility for a research study. Typically, this is a medical doctor or someone with a doctorate degree in a health field. The Principal Investigator (PI) makes sure that the research follows good scientific and ethical practices and that it can answer the research questions being asked (often, being asked by a study sponsor). The PI also oversees the research support staff.

Protected Health Information (PHI)

Protected Health Information (PHI) refers to personal health-related information that is shared between individuals or organizations who provide treatment, payment, and operations in healthcare. For example, this can include Medical Record Numbers, hospital bills, lab reports, etc. 

It’s important to note that PHI is different from PII. PII is an umbrella term for any information that can be traced to an individual’s identity, while PHI refers specifically to identifiable health information possessed by HIPAA covered entities. 

Protected group

Groups of people who are provided additional protections in health research based on federal regulations. In some cases, individuals in these groups may not be able to legally consent to participating in research by themselves and may require consent to be given by a caregiver or legally authorized representative. 

Examples of protected groups include children, pregnant women, and prisoners. 

Randomized Controlled Trial (RCT)

A study in which researchers randomly assign participants to different groups (also called arms or cohorts). The goal is to minimize bias and then compare the study results between the groups.

For example, a study may randomly assign participants to take either a new medication or a sugar tablet every day. The researchers will then use the data from participants to learn if the medication made a difference for the group that received it.

Real-world evidence

Clinical evidence that is generated from real-world data about the use, risks, and/or benefits of a medication, product, or treatment. 

Real-world data

Data about the use, risks, and/or benefits of a medication, product, or treatment that come from a variety of sources. For example, real-world data can come from clinical sources like electronic health records, claims and billing activities, product and disease registries. Or it can come from everyday sources like health apps and fitness trackers. 


The process of using scientific methods to collect, analyze, and interpret data collected from studies to contribute to knowledge about a topic. 

Research site

A location where research is conducted. This can include hospitals, universities, private medical practices, research institutes, and more. 


A sponsor may be an individual or pharmaceutical company, governmental agency, academic institution, private organization, or other group that initiates, oversees, and/or is financially responsible for the research. 

For example, a pharmaceutical company may initiate research to learn if the drug they make works, and pay another independent organization to actually conduct the study. 


Where research methods are used to collect, analyze, and interpret data collected from participants to contribute to knowledge about a topic. 

Study data

Information collected during a research study. It can include demographic information (race, age, education level), health information, descriptions of the participant’s progress, and other relevant information.


The process of exiting a research study or trial. All research studies are voluntary, which means that participants are free to stop participating at any time for any reason.

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