Properties of psychological variables at the mean or variance level can differ between persons and within persons across multiple time points. For example, cross-sectional findings between persons of different ages do not necessarily reflect the development of a single person over time. Recently, there has been an increased interest in the…

This paper demonstrates how Q-methodology combines artistic and scientific procedures to allow social science researchers to develop and test theories about differences in persons. Q-methodology is based on factor analysis. In R-technique factor analysis, the most commonly used technique, variables define the columns and persons define the rows of…