A researcher conducts a t test for dependent menas in which it is predicted that there will be a decrease in unemployment from before to after a particular job-skills training program. The cutoff "t" needed is -1.8333. The standard deviation of the distribution of menas 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?
To calculate the effect size in this scenario, you will need the mean change score and the standard deviation of the distribution of means of change scores. The effect size can be calculated using Cohen's d formula.
Cohen's d = (mean change score) / (standard deviation of the distribution of means of change scores)
In this case, the mean change score is an increase of 5.2, and the standard deviation of the distribution of means of change scores is 2.0. Therefore, the calculation becomes:
Cohen's d = 5.2 / 2.0
Cohen's d ≈ 2.6 / 2.0
Cohen's d ≈ 1.3
So, the effect size in this context is approximately 1.3.