The two major research approaches—nonexperimental and experimental—offer different yet complementary methods to investigate a question, to evaluate a theory, and to test a hypothesis.
Both approaches can call upon a toolbox of methods and study designs, and all are evaluated on the basis of reliability and validity.
Science focuses only on peer-reviewed research, which is evaluated using principles of reliability and validity.
Cross-cultural research reinforces the critical importance of reliability and validity in evaluating evidence and in optimizing the generalizability of psychological knowledge.
