Question

On a standard test, the population is known to have a mean of 500 and a standard deviation of 100. Those receiving an experimental treatment have a mean of 540. The effect size is \(\_\_\_\_\_\_\) (rounded off to two decimal places).

Hint:

Effect size provides a standardized measure of the magnitude of an effect, independent of sample size.

Answer 1

Effect size quantifies the difference between group means: 
Effect size = \(\frac{\text{Mean of experimental group - Mean of population}}{\text{Standard deviation}} \)
Effect size = \(\frac{540 - 500}{100} = 0.40\) Thus, the effect size is 0.40.