ABSTRACT
This book is intended to help researchers, students, and teachers in clinical, educational, and other areas involving human participants. Research in these areas is often aimed at testing the efficacy of a treatment or intervention in improving some measure of health or well-being. Psychologists seeking to understand human behavior also often test the effect of an intervention, treatment, or other experimental condition. There are well-established procedures for designing experiments where treatments or interventions can be randomly allocated to large numbers of participants who are representative of a well-defined population. We refer to such designs as large-n or large-group designs. Tests such as t tests and analysis of variance (ANOVA), known collectively as parametric tests, generally provide valid analyses of such designs provided some assumptions about the data are approximately met.
