Multilevel theories, multi-stage sampling, and multilevel models -- Statistical treatment of clustered data -- The random intercept model -- The hierarchical linear model -- Testing and model specification -- How much does the model explain? -- Heteroscedasticity -- Missing data -- Assumptions of the hierarchical linear model -- Designing multilevel studies -- Other methods and models -- Imperfect hierarchies -- Survey weights -- Longitudinal data -- Multivariate multilevel models -- Discrete dependent variables -- Software.