Stanley Milgram's obedience studies effectively illustrate how researchers can use experimental and non-experimental approaches in complementary ways. Milgram began with a non-experimental, observational study where he measured a single variable—the extent to which participants obeyed instructions to shock a confederate under identical conditions. Following this descriptive phase, he subsequently conducted controlled experiments where he systematically manipulated independent variables, such as the physical distance between the experimenter and the participant, to explore the specific factors that causally affect the rate of obedience.