If two or more variables affect each other, we will talk of a statistical dependence or relationship. The strength of a dependence between variables can be measured simultaneously – for example, we could investigate to what extent the looks of a person influence his personal income and vice versa. The grade of such a relationship is referred to as correlation and can be measured by methods such as the Spearman's rank correlation coefficient.
Please note that the definitions in our statistics encyclopedia are simplified explanations of terms. Our goal is to make the definitions accessible for a broad audience; thus it is possible that some definitions do not adhere entirely to scientific standards.