Glossary of Clinical Research - H

H

• Healthy control

In a clinical study, a person who does not have the disorder or disease being studied. Results from healthy controls are compared to results from the group being studied. (NCI)

• Historic cohort study

A research study in which the medical records of groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke and those who do not smoke) are compared for a particular outcome. Also called a retrospective cohort study. (NCI)

• Historical control subject

An individual treated in the past and used in a comparison group when researchers analyze the results of a clinical study that had no control group. The use of a control, or comparison, group helps researchers determine the effects of a new treatment more accurately. (NCI)

• Human subject

An individual who is or becomes a participant in research, either as a recipient of the test article or as a control. A subject may be either a healthy human or a patient. (21CFR50.3)

• Hypothesis

A supposition or assumption advanced as a basis for reasoning or argument, or as a guide to experimental investigation. (NLM)