methods
An alternative to ∗OLS regression models used when data are found in ∗nested categories or levels, such as college students taking Sociology 201, sociology majors, majors in any of the social sciences, undergraduates in the university, or undergraduates in the state. The method's advantage is that it makes it possible to separate the variance into components explaining the effects of different levels of analysis, such as the effects of a course, of a major, or of being undergraduates. [Source: Dictionary of Statistics & Methodology; Hierarchical Linear Models (HLM)]
hierarchical linear models
multilevel analysis
statistics