Preface process of variable selection and sample size/power calculations. Sources of study bias/error are briefly described, as are statistical tools for decision making. The second part of this chapter uses the foundation set out by the primer to focus specifically on informatics-related evaluations. Two areas serve as focal points evaluating information retrieval (IR) systems, including content-based image retrieval; and assessing(system)usabilityxiv Preface process of variable selection and sample size/power calculations. Sources of study bias/error are briefly described, as are statistical tools for decision making. The second part of this chapter uses the foundation set out by the primer to focus specifically on informatics-related evaluations. Two areas serve as focal points: evaluating information retrieval (IR) systems, including content-based image retrieval; and assessing (system) usability