Physical Sciences
A certain solder joint on the undercarriage of a city bus is being tested for shear strength. A sample of solder joints was randomly selected, and the shear strength for each was measured (in N) before (x) and after (y) temperature-cycle stress. The data are given in the following table.
a. Rank the observations in each sample separately, and find each difference between the ranks, di.
b. Find the sample correlation coefficient between the ranks.
c. Find Spearman's rank correlation coefficient using the di's.
d. Explain why the values in parts (b) and (c) are different, and use these results to explain the relationship between the two variables.