Random intercept models: When intercepts vary
Robson, K., & Pevalin, D. (2016). Random intercept models: When intercepts vary. Multilevel modeling in plain language (pp. 21-65). SAGE Publications Ltd.
This chapter discusses the random intercept models. These are models in which the intercept is allowed to vary for each Level 2 group; this is the random part of the model. The chapter starts with a quick review of ordinary regression before easing into the random intercept models. It offers a step-by-step approach to exploring the data and specifying models with main effects and interaction effects.