Suppose that you are interested in examining the effects of the transition from fetal to postnatal circulation among premature infants. For each of the 14 healthy newborns, respiratory rate is measured at two different times--once when the infant is less than 15 days old and again when she is more than 25 days old.
Subject Time 1 Time 2 +/- Diff/rank Signed rank
1 62 46
2 35 42
3 38 40
4 80 42
5 48 36
6 48 46
7 68 45
8 26 40
9 48 42
10 27 40
11 43 46
12 67 31
13 52 44
14 88 48
a. Using the sign test, evaluate the null hypothesis that the median difference in respiratory rates for the two times is equal to 0?
b. Evaluate the same hypothesis using the Wilcoxon signed-rank test?
c. Do you reach the same conclusion in each case?