Exploring the intersection of ethics and statistics, this comprehensive guide illustrates the proper use of probabilistic and statistical reasoning in the behavioral, social, and biomedical sciences. Lauded for their contributions to statistics, psychology, and psychometrics, the authors make statistical methods relevant to readers'' day-to-day lives by including real historical situations that demonstrate the role of statistics in reasoning and decision making. In addition, seven U.S. Supreme Court decisions reflect the influence of statistical and psychometric reasoning and interpretation/misinterpretation.