1. an experimental method used to investigate the behavior and psychological processes and functioning of individuals in social and other environments—often those which investigators cannot easily access—by reproducing those environments in a realistic way. For example, simulations are often used in personnel selection, where various exercises have been developed to tap job-related dimensions or behaviors.

2. the artificial creation of experimental data through the use of a mathematical or computer model. The purpose is usually to test the behavior of a statistic or model under controlled conditions.

3. resemblance or imitation, particularly the mimicking of symptoms of one disorder by another or the faking of an illness.