Ch. 7 REVIEW PROBLEMS 241 



Freshmen {Continued) 

 ACE-T ACE-L ACE-Q GPA ACE-T ACE-L ACE-Q GPA 



Juniors 



64. Make scatter diagrams of the total ACE scores (ACE-T's) on the hori- 

 zontal axis and the GPA's on the vertical for freshmen and also for juniors, 

 using the same coordinate system but different symbols for the two classes. 



65. After solving the preceding problem, explain why you agree or disagree 

 with each of the following statements: 



(a) For freshmen, you would expect to find a positive and useful linear cor- 

 relation between these two variables; but there also are other important factors 

 affecting the grade point average of a college student. 



(6) For the juniors represented by this sample, there is little, or no, relation- 

 ship between the ACE-T score and the grade point average. 



(c) The freshmen and the juniors fit the same general relationship between 

 ACE-T and GPA; the persons with especially low ACE-T scores simply have 

 been eliminated by the time of the junior year. 



(d) Given that for freshmen the linear correlation between GPA and ACE-L 

 score is .6, whereas that between GPA and ACE-Q is only .4 for these samples, 

 it is concluded that whatever is measured by the L-score definitely is more 

 important than whatever is measured by the Q-score. 



66. Make a scatter diagram for the ACE-L scores of freshmen against their 

 GPA's. And then do likewise for the juniors, using the same coordinate axes. 

 Draw appropriate conclusions. 



67. Solve as in problem 65, parts (a) to (c), but use the results of problem 

 66 and change ACE-T to &CE-L wherever used. 



68. Compute the Spearman rank-difference correlation, r g , for each scatter 

 diagram of problem 64. Then consider problem 65 in the light of these cor- 

 relations. Ans. For freshmen, r = .59; for juniors, r„ = .14. 



