What does correlation measure?

Correlation measures the relationship between two variables, assessing the extent to which they change together. A correlation indicates whether an increase in one variable is associated with an increase or decrease in another variable, but it does not determine the cause or effect relationship.

For instance, if two variables are correlated positively, it means that as one variable increases, the other also tends to increase. Conversely, a negative correlation indicates that as one variable increases, the other tends to decrease.

This is distinct from measuring effects or causation—where one variable influences another, as indicated in the first option. Correlation does not imply causation; it simply highlights a statistical association. Therefore, while interactions between variables could also involve correlation, they encompass broader concepts that might include more than just the relationship itself.