  In this paper, I outline several conceptual and methodological issues related to modeling individual and group processes embedded in clustered/hierarchical data structures. We position multilevel modeling techniques within a broader set of univariate and multivariate methods commonly used to study different types of data structures. We then illustrate how the choice of analysis method affects how best to examine the data. This overview gives us an idea of our further development of these themes and models in this study. 
Introduction to Multilevel Modeling Techniques