Causality and predictability

Here are two final points you should keep in mind:

First, the presence of a correlation between two variables doesn't prove that certain values on one variable cause high or low values on the other. It merely demonstrates that the two variables are associated in some way.

Second, the relationship between two correlated variables has predictive value. This means that if a strong correlation exists between variables, then knowing a person's score on one variable allows us to predict a person's score on the other variable.