Question

My Research Methods class (N = 14) was interested in whether studying alone or in groups would result in better grades on their third assignment. Half of the class (n = 7) studied for the assignment alone, while the other half (n = 7) studied as a group. Their grades are summarized in the below tables:

Study Alone
Student	Grade
1	78%
2	97%
3	79%
4	90%
5	91%
6	74%
7	72%

Study in Group
Student	Grade
8	72%
9	89%
10	77%
11	87%
12	89%
13	77%
14	69%

1. What are the upper and lower boundaries of the range of differences between two μs that you can say with 95% confidence contains the difference represented by the above sample?

2. Using Cohen’s d, calculate the effect size of studying alone vs. in a group on the grade obtained. What is the strength of this relationship and why?

Answer 1