In each of the studies in the accompanying table using difference​ scores, test the significance using a t test for dependent means. Include an estimate of effect size and whether it is considered approximately​ small, medium, or large. Study Number of Difference Scores in Sample Mean of Difference Scores in Sample Estimated Population Variance of Difference Scores Tails Significance Level ​(a) 20 1.30 8.03 1​ (high predicted) 0.05 ​(b) 164 2.60 414.02 2 0.05 ​(c) 15 negative 2.40 4.38 1​ (low predicted) 0.01 pop-up content ends

Click here to view Cutoff Scores for the t Distribution.LOADING... Question content area bottom Part 1 For Study​ (a), let the first population be the one from which the sample is taken and let the second population be the one whose mean difference is 0. What is the research hypothesis for this​ test? Choose the correct answer below. A. The mean difference for the first population is greater than the mean difference for the second population. B. The mean difference for the first population is different from the mean difference for the second population. C. The mean difference for the first population is the same as the mean difference for the second population. D. The mean difference for the first population is less than the mean difference for the second population.