This document discusses common methods used in psychological research. It describes introspection, observation, life-history method, survey method, experimental method, and statistical method. Introspection involves self-analysis of one's own feelings and experiences. Observation can be uncontrolled, naturalistic, or controlled. The life-history method traces the development of behaviors through methods like diaries. Surveys collect data through questionnaires or interviews from a representative sample. Experiments involve manipulating an independent variable to measure its effects on a dependent variable. Statistics are used to analyze numerical data and make inferences.