This volume offers a basic introduction to a variety of elementary statistical techniques, including those for summarizing data, analysing differences between groups and examining relationships between measures. How to Analyze Data is a revision of the first edition volume How to Calculate Statistics. While many of the techniques described are the same as those in the original version, several infrequently applied ones have been excluded, and treatment of Effect Size, a relatively recent and simple approach to examining differences between groups, has been added. Moreover, the book has been significantly expanded with three important new chapters. A concerted effort has been made to include only the most basic and widely used statistical techniques that are appropriate for answering essential evaluation questions. Worksheets and practical examples are included throughout.