This document provides information about quantitative research methodology, specifically causal-comparative research. Causal-comparative research aims to determine the cause of existing differences among groups by comparing two or more groups in which the independent variable is not manipulated. It differs from experimental research in that the independent variable has already occurred. Survey research is also discussed as a popular technique for collecting primary data through interaction with people to obtain facts, opinions, and attitudes. Various types of surveys like cross-sectional, longitudinal, and their designs are explained.