22. problem 13 in chapter 10 presented data showing that varsity athletes in contact sports (football and hockey) who were regularly exposed to head impacts had significantly lower cognitive scores than varsity athletes from noncontact sports. the independent measures t test produced t = 2.25 with df = 14 and a value of r2 = 0.265 (26.5%). a. convert the data from this problem into a form suitable for the point-biserial correlation (use 1 for the noncontact athletes and 0 for the contact athletes), and then compute the correlation. b. square the value of the point-biserial correlation to verify that you obtain the same r2 value that was computed in chapter 10. gravetter, frederick j. statistics for the behavioral sciences (p. 527). cengage learning. kindle edition.