Skip to Main Content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.

Research Methods Help Guide

Basic information on research methods concepts.

More Information

Definitions You Need to Know

Constant: a fixed value. Not a variable.

Variable: a value or characteristic that differs among individuals. It can be described, counted, or measured.

Independent Variable: the variable researchers manipulate in an experiment. Affects the dependent variable(s).

Dependent Variable: the variable affected by the independent variable in an experiment.

Sample: a smaller group selected from a larger group (the population). Researchers study samples to draw conclusions about the larger group.

Population: the entire collection of people, animals, plants, things, etc. researchers wish to examine. Since populations are often too large to include every member in a study, researchers work with samples to describe or draw conclusions about the entire population group using statistical tests.

Participant: an individual who participates in a study. This is a more recent term. (Used with human research.)

Subject: another way to describe a participant. This is a more traditional term. (Used with human and animal research.)

Attrition: loss of participants/subjects in a study.

Reliability: the extent to which a measure or tool yields consistent results on repeated trials.

Validity: the degree to which a study accurately assesses what it is attempting to assess.