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Multilevel Modeling: Current and Future Applications in Personality Research


  • The online version of this article contains additional supporting information, including (a) a more detailed description of the method used to simulate the data presented in this article and the corresponding SAS computer script and (b) SAS and SPSS computer script for all analyses reported in this article.

concerning this article should be addressed to Stephen G. West, Psychology Department, Arizona State University, Tempe, AZ 85287-1104. Email:


ABSTRACT Traditional statistical analyses can be compromised when data are collected from groups or multiple observations are collected from individuals. We present an introduction to multilevel models designed to address dependency in data. We review current use of multilevel modeling in 3 personality journals showing use concentrated in the 2 areas of experience sampling and longitudinal growth. Using an empirical example, we illustrate specification and interpretation of the results of series of models as predictor variables are introduced at Levels 1 and 2. Attention is given to possible trends and cycles in longitudinal data and to different forms of centering. We consider issues that may arise in estimation, model comparison, model evaluation, and data evaluation (outliers), highlighting similarities to and differences from standard regression approaches. Finally, we consider newer developments, including 3-level models, cross-classified models, nonstandard (limited) dependent variables, multilevel structural equation modeling, and nonlinear growth. Multilevel approaches both address traditional problems of dependency in data and provide personality researchers with the opportunity to ask new questions of their data.