This text provides undergraduate students with a practical introduction to the design and analysis of experiments, particularly in the social and behavioral sciences. Its straight forward approach, step-by-step descriptions, worked examples, and exercises should combine to make important concepts and methods more accessible to readers of diverse backgrounds. For its second edition the book has been revised to give a clearer understanding of how experiments are designed and how the results are interpreted. It features: a new chapter on estimation procedures; a new chapter on the analysis of two-factor within-subjects design; a new chapter combining discussions of type I, II, and cumulative type I errors with expanded coverage of error control and sample size; a revised discussion of linear correlation and regression; expanded discussions of the analysis of experiments with more detailed examinations of power and effect size and additional problems and exercises, some with detailed answers provided in an appendix.