A Professor Wants to Compare the Test Scores of His

Multiple Choice

A professor wants to compare the test scores of his two psychology classes (Class A and Class B) . Each class has 20 students. The professor calculates a t value of 2.3 and concludes that Class B has a mean test score that is significantly higher than Class A. What is the effect size associated with this statistical test?

A) .12
B) .24
C) .35
D) .48