Multi‐Level Modeling

Whenever research is concerned with the analysis of relationships between lowerlevel units (e.g., individuals) and the higherlevel unit they belong to (e.g., group), a hierarchical – multilevel or nested – data structure occurs. In such cases, multi-level modeling (MLM) approaches, also known as hierarchical linear modeling, are suited to empirically assess respective data structures in a methodologically correct way. The article gives an introduction to the background of multilevel modeling, outlines the methodological procedure for the basic case of a two-level model, and provides an outlook to more advanced applications of MLM. Keywords: multilevel modeling; levels of analysis; nested data; hierarchical linear modeling; within-group regression; between group regression