A research participant, also called a human subject or an experiment, trial, or study participant or subject, is a person who participates in human subject research by being the target of observation by researchers.
In accordance with modern norms of research ethics and with the Declaration of Helsinki, researchers who conduct human subject research should afford certain rights to research participants. Research participants should expect the following:
There are several standard themes in the choice of words (participant, subject, patient, control):
In scientific publishing, many usage commentators prefer the term participant rather than subject because the latter has a connotation to some readers of limited autonomy, as if the person were in a subservient or uninformed role. In contrast, participant connotes active consent, involvement, and awareness.
In retrospective studies such as chart-review studies, the word participant may be a poor choice, because the persons being studied are not actively participating (and they may not even be aware of the particular study, although they have consented to the idea that their data may be included in scientific studies when sufficiently anonymized). Therefore, replacing the word subject with participant is only conditionally (not universally) appropriate. In most such studies, the word patient may be preferable to subject, as long as all of the subjects in that study were patients (see next point).
Not all participants are patients. Some are healthy controls. In some study designs, all the participants are patients; but in others, only some of them are. Therefore, replacing the word subject with patient is only conditionally (not universally) appropriate.
A case is an instance of disease. A patient is a person. Patients are not cases. When writing, investigators should use the words appropriately. For example, a 55-year-old patient with melanoma is not a 55-year-old case of melanoma.
In case-control studies especially, many instances of this distinction may arise. Although it is accepted to refer to control-group participants as controls, it is poor writing to refer to case-group participants as cases. Instead, the term case participants is used; and control participants is parallel to it.