Descriptive studies, sometimes called observational studies, are done to identify or clarify characteristics of specific populations. Questionnaires, interviews, and surveys are often used for this purpose. Knowing characteristics of a population can aid in the prediction of potential problems in that population as well as the development of intervention strategies. When two or more groups (cohorts) are sampled in a descriptive study, data can be compared to determine similarities and differences.

Examples of variables examined in such research include attitudes, opinions, beliefs, and/or eating habits. Relationships between variables can be determined to determine associations or a lack thereof.

A survey can be administered once (cross-sectional) or repeated over time (longitudinal). Survey research is limited by the subject's willingness to report information (and report it accurately), and by response rate. Often, 100% of those surveyed do not respond to a given survey, which can bias the results if there is a difference in attitude or behaviors of the respondents and nonrespondents.

Descriptive studies can be considered a type of epidemiological research.