In the first two parts of this book I discussed general considerations and procedures for analyzing test scores and procedures for assuring that these scores are as reliable as needed for the intended uses of the test. All of these analyses help us obtain information that pertains to the statistical and measurement characteristics of test scores. However, the reason we give tests and obtain scores is so that we can make inferences about what individuals know or can do, and to make decisions on the basis of these inferences. In this final section, I will describe how to use statistics to help us determine if the differences and relationships we observe among sets of test scores can be interpreted as indicating ‘real’ differences or relationships, procedures for investigating the extent to which the test scores we obtain are valid indicators of the abilities we want to measure, and how to make use of scores for reporting results in meaningful ways.

The four chapters in this part of the book discuss procedures that enable us to use test scores in meaningful ways. Chapter 7 describes the logic of hypothesis testing and statistical inference, while Chapter 8 describes statistical procedures for testing for statistical significance. Chapter 9 discusses the logic and statistical procedures for investigating the validity of the uses we make of test scores. Chapter 10 describes ways in which we can report test results in meaningful ways to different groups of test users.