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 job-skills 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
The effect size measures the magnitude of the difference between the two groups being compared. In this case, the effect size is calculated using the mean change score and the cutoff "t" value.
To calculate the effect size, we divide the mean change score by the cutoff "t" value. In this case, the mean change score is 5.2 and the cutoff "t" value is -1.8333.
So, the effect size would be:
5.2 / -1.8333 ≈ -2.84
Next, we interpret the effect size. There are different ways to interpret the effect size depending on the context and field of study. However, in general, an effect size of -2.84 would be considered large.
Therefore, the correct answer is:
5.2 / -1.8333 = -2.84; large.