Helping the reader to understand how the science of statistics works and to make informed decisions about the world we live in, this text offers a step-by-step approach to statistical tests instead of using formulas by rote. The fourth edition features a wealth of real-world examples, exercises in R, advice for working with larger datasets, new coverage of alternative non-parametric tests and an expanded discussion of confidence intervals. Every chapter also includes a short story about historical or contemporary statisticians who helped advance statistics through unique applications.