There are times when it is important to compare the scores of different types of data that are scored in different units or to compare scores within a sample or a population. One common example is that students typically want to understand how their test score compares with the scores of the rest of the class. Or they might want to understand how their scores compare across different classes, which could each be scored using somewhat different methods. In either case, the challenge is somewhat like attempting to compare apples with oranges. A standardized score is calculated on an arbitrary (but universal) scale, which has the effect of turning the apples and oranges into pears, scores that can be more easily evaluated and interpreted. In ...