30 - Analyzing personality change: From average trajectories to within-person dynamics

Abstract

The goal of this chapter is to review common approaches to the analysis of personality change by means of longitudinal data. Based on selected statistical models, it will be shown how the fields of personality psychology and psychological methods have progressed from the description of average trajectories to the analysis of within-person dynamics. We begin (1) with a short review of traditional models for the analysis of change and demonstrate how latent trajectory models overcome limitations associated with the strictly nomothetic perspective of the former. Next (2), dynamic models of change are introduced and we show how their increasing popularity reflects the desire to move from a rather descriptive account of personality change toward an explanatory account of the underlying mechanisms. In the third part (3), we demonstrate how careless adoption of idiographic time series models to large sample panel models may create unique problems due to heterogeneity across individuals and time and discuss recent developments to address these problems. Throughout this chapter, we will use an example dataset and provide R-code to illustrate the specification, estimation, and interpretation of selected models. The purpose of this chapter is not to give a full account of methods available to study personality change, but rather to identify some general trends, discuss common problems, and point the reader to ongoing developments.