This is the leading text for social work statistics courses because of its accessibility and the fact that it assumes no prior background in statistics. This text can be used in introductory-level statistics courses or as part of the research methods sequence in social work. It includes numerous social work practice examples, and discusses types of statistical analyses that are most likely to be encountered by social work practitioners and researchers. This edition has been reorganized and updated, with new content added on statistical power, effect size, and measures of association. New topics have been incorporated, including logistic regression and other methods of analysis not in prior editions. New figures and new content on sampling distributions and standard scores (z-scores) have also been added.