Example 8.1.1: Paired Design Doctors studying healthy subjects measured myocardial blood flow (MBF) during bicycle exercise before and after giving the subjects a dose of caffeine that was equivalent to drinking two cups of coffee.

Example: Paired Hypothesis Testing A researcher wants to know how the temperature affects the number of bristles on each fruit flies. The difficulty is that she has 12 fruit flies from 6 different lines (2 of each) and there is no reason to expect that the different lines of fruit flies will have the same number of bristles. She thinks that the bristle number has approximately a normal distribution, but the flies from the same line should have similar bristle numbers.

Example: Paired Hypothesis Testing (cont) ColdWarmDifference Liney1y1 y2y2 d = y 1 – y mean s SE

Example: Paired Hypothesis Testing (cont) ColdWarmDifference Liney1y1 y2y2 d = y 1 – y mean s SE

Example: Paired Hypothesis Testing (cont) ColdWarmDifference Liney1y1 y2y2 d = y 1 – y mean3536 s SE

Paired tests: Summary

Table 7: Critical values for Sign Test

Example 8.4.1*: Sign Test Skin grafts are applied to both sides of the body in 11 recipients. One graft has a close HL-A match with the recipient; the other does not. Observe the time it takes to reject each skin graft. Does a good HL-A match increase graft survival time with a significance of  = 0.05?

Example 8.4.1*: Sign Test (cont) HL-A Compatibility ClosePoorSign of PatientY1Y1 Y2Y2 d = Y 1 – Y

Example 8.4.1*: Sign Test (cont) HLA Compatibility ClosePoorSign of PatientY1Y1 Y2Y2 d = Y 1 – Y

Example: Before-after studies vs. Control