Stub entry: single definition derived from the NIST trustworthy-AI glossary; sector-specific readings not yet documented — contributions welcome.
(control group) the set of observations in an experiment or prospective study that do not receive the experimental treatment(s). These observations serve (a) as a comparison point to evaluate the magnitude and significance of each experimental treatment, (b) as a reality check to compare the current observations with previous observation history, and (c) as a source of data for establishing the natural experimental error.
NIST AIRC, The Language of Trustworthy AI glossary (public-domain compilation), entry 'control class', definition attributed to nist_statistics_2012