ABSTRACT
A statistician named Karl Pearson developed a very widely used statistic for describing the relationship between two variables (see Section 12 for a discussion of the correlation between two variables). The symbol for Pearson’s statistic is a lowercase, italicized letter r, and it is often called the Pearson r. Its full, formal name is the Pearson product-moment correlation coefficient, and there are variations on the name in research literature, such as the Pearson correlation coefficient or the product-moment correlation coefficient. These are some of the basic properties of the Pearson r:
1. It can range only from –1.00 to 1.00.
