A measure of effect size is a statistic that measures the ______.

A) direction of the relationship between variables
B) nature of the relationship between variables
C) magnitude of the relationship between the sample and population
D) magnitude of the relationship between variables

A measure of effect size tells us about the magnitude of the relationship between variables, which is different from just knowing the direction or nature of the relationship. It gives us an idea of the strength and importance of the relationship, and allows us to compare different studies or interventions.