AP PSYCHOLOGY

Detailed explanation-1: -The only method that will establish a cause-and-effect relationship is an experimental research design. A true experiment must feature a control group as one of the experimental groups, along with random sampling from the population and random assignment of the study subjects to the experimental groups.

Detailed explanation-2: -For nearly as long as the word ‘correlation’ has been part of statistical parlance, students have been warned that correlation does not prove causation, and that only experimental studies, e.g., randomized clinical trials, can establish the existence of a causal relationship.

Detailed explanation-3: -Causal research, also known as explanatory research is conducted in order to identify the extent and nature of cause-and-effect relationships. Causal research can be conducted in order to assess impacts of specific changes on existing norms, various processes etc.