Similar to the placebo effect in medicine, this effect occurs when people change their behavior simply as a result of being a participant in a research study or because they know that they are being observed. The behavioral change is usually in a socially acceptable direction. [Source: The SAGE Glossary of the Social and Behavioral Sciences; Hawthorne Effect (Psychology)]
Hawthorne effect
methods
evaluation, testing, and research methods
statistics and research methods
theories, models, and philosophical perspectives