Statistics
posted by stat .
A researcher conducts a t test for dependent means in which it is predicted that there will be a decrease in unemployment from before to after a particular jobskills training program. The cutoff "t" needed is 1.8333. The standard deviation of the distribution of means of change scores is 2.0 and the mean change score for the sample studied is an increase of 5.2.
What is the effect size?
5.2/1.833 = 2.84; large
2/5.2 = .38; approximately medium
5.2/2 = 2.60; large
It can not be determined without also knowing the population standard deviation

Check out the third choice.