Pearson Product Moment Coefficient of Correlation

Abstract

In the first seven chapters of this text, we have dealt with situations in which each one of the N people in our study had a score, X, on some test or other measurement. It is now time for us to expand our view and consider the perfectly realistic situation in which each individual may have scores on two (or more) different variables. Suppose that we have the height and weight of each one of a group of 12-year-old girls. We can, of course, compute the mean and standard deviation of height; and we can do the same for weight. But a more important question may well be: Is there a correlation, or relationship, between height and weight? Are the tall girls apt to weigh more or less than the short girls? Do the heavy girls tend to be above or below the average in height?