So far, you have been reading about statistics that describe sets of data. In many research studies, psychologists might want to know the extent to which two variables are related.
Correlational statistics do just that.
Correlational statistics yield a number called the coefficient of correlation. The coefficient may be positive or negative and may vary from -1.00 to 1.00. In a positive correlation, scores on two different variables increase and decrease together. For example, there is a positive correlation between high school GPA and freshman GPA in college. If a student has a score above average on one of the variables of interest, then they likely will have a score above average on the other variable of interest.