The following data on x 5 score on a measure of test anxiety and y 5 exam score for a sample of n 5 9 students are consistent with summary quantities given in the paper “Effects of Humor on Test Anxiety and Performance” (Psychological Reports [1999]: 1203–1212):

x 23 14 14 0 17 20 20 15 21 y 43 59 48 77 50 52 46 51 51 Higher values for x indicate higher levels of anxiety.

a. Construct a scatterplot, and comment on the features of the plot.

b. Does there appear to be a linear relationship between the two variables? How would you characterize the relationship?

c. Compute the value of the correlation coef fi cient. Is the value of r consistent with your answer to Part (b)?

d. Is it reasonable to conclude that test anxiety caused poor exam performance? Explain.