A common concern for students (and teachers) is the assignment of grades for essays or term papers.

Because there are no absolute right or wrong answers, these grades must be based on a judgment of quality.

To demonstrate that these judgments actually are reliable, an English instructor asked a colleague to rank-order a set of term papers. The ranks and the instructor’s grades for these papers are as follows:
Rank Grade 1 A 2 B 3 A 4 B 5 B 6 C 7 D 8 C 9 C 10 D 11 F

a. Compute the Spearman correlation for these data.
(Note: You must convert the letter grades to ranks, using tied ranks to represent tied grades.)

b. Is the Spearman correlation statistically significant? Use a two-tailed test with α = .05.