To test the effectiveness of a new studying strategy, a teacher randomly divides a sample of 8 students into tow groups, with n = 4 in each group. The students in group one receive training in the new studying strategy. Then all students are given 30 minutes to study a chapter before taking a quiz. The quiz scores for the two groups are as follows.
Training No Training
9 4
7 7
6 3
10 6
a. Convert these data into a form suitable for the point-biserial correlation. (Use X =1 for training, X = 0 for no training, and the quiz score for Y.)
b. Calculate the point-biserial correlation for these data