## ABSTRACT

This chapter looks at nested data. In Chapter 1, we considered the standard linear model that underlies such common statistical methods as regression and analysis of variance (ANOVA; i.e. the general linear model). In the example described in Chapter 1, there was nothing linking their dependent variable values other than the independent variables included in the linear model. However, in many cases the method used for selecting the sample does create the correlated responses among individuals. We typically refer to the data structure described above as nested, meaning that individual data points at one level (e.g. student) appear in only one level of a higher-level variable such as a school. Thus, students are nested within a school. Such designs can be contrasted with a crossed data structure whereby individuals at the first level appear in multiple levels of the second variable.