Beginning with an overview of the history and uses of statistics, this booklet defines the terms 'samples' and 'populations,' as well as common statistical symbols. Statistical operations that police officers are likely to encounter are described, such as frequency distribution, polygon, and historgram. Procedures are then detailed for computing percentages, averages, the normal curve, variability, and correlations. The discussion of nonparametric techniques focuses on computation for chi square. The use of statistical tables is explained through calculating the rank difference coefficient of correlation. A review of methods to measure discrete and continuous data is followed by descriptions of random, stratified, and incidental samples. Noting that the collection of data is the most important function of statistical research, the guide recommends that a detailed design be developed before any research project is implemented. Finally, a research problem concerning a police communications system in an area of multiple jurisdictions is provided to demonstrate one approach to collecting and analyzing statistical data. Instructional aids, tables, and review questions are included.