ABSTRACT
Statistical Guide: When there is a relationship between two variables, we can use the scores on one of the variables to predict scores on the other. For example, college admissions officers usually have data that enable them to predict college GP As from high school GP As. The predictor variable is called X (in this case, high school GPA), and the criterion or outcome that is being predicted is called Y (in this case, college GPA). Using the data for those being admitted to college this year, the officer computes the intercept (a) and the slope (b) for the straight line that best describes the dots on a scattergram. (To review scattergrams, see Exercise 15). The values of a and b are then substituted in this formula:
Y= a +bX When a new student applies, the officer predicts Y (college GP A) by substituting the student's high school GP A for X.
