ABSTRACT
The analyses discussed in this chapter are used in a design with one independent variable, with two or more levels or conditions, and participants are measured under all conditions. These designs are referred to as within-subjects, dependent-sampks, or repeated-measures designs, and we use these terms interchangeably here. This means that participants undergo all conditions of the study or participants are matched on some variable(s) assumed to be related to the dependent variable. The types of research approaches used with single-factor, repeated-measures designs are often randomized experimental or quasi-experimental. The comparative approach with a within-subjects design and analysis is used to compare participants who vary on an attribute independent variable if they are matched (e.g., pairs of students with and without attention deficit hyperactivity disorder matched on IQ and gender). The comparative approach is also used when a cohort of participants is followed longitudinally to study developmental change (i.e., they are assessed on the same measures two or more times without any planned intervention between assessments).
