Studies have shown that heating the scrotum by just 1C can reduce sperm count and sperm quality, with long-term consequences. Exercise 2.101 on page 87 introduces a study indicating that males sitting with a laptop on their laps have increased scrotal temperatures. Does a lap pad help reduce the temperature increase? Does sitting with legs apart help? The study investigated all three of these conditions: legs together and a laptop computer on the lap, legs apart and a laptop computer on the lap, and legs together with a lap pad under the laptop computer. Scrotal temperature increase over a 60-minute session was measured in^—¦C, and the summary statistics are given in Table 8.3.  

Table 8.3

(a) Which condition has the largest mean temperature increase? Which has the smallest?

(b) Do the data appear to satisfy the condition that the standard deviations are roughly the same? (The data satisfy the normality condition.)
(c) Use the fact that sum of squares for groups is 13.7 and error sum of squares is 53.2 to test whether there is a difference in mean temperature increase between the three conditions. Show all details of the test, including an analysis of variance table.

Exercise 2.101 on page 87

Studies have shown that heating the scrotum by just 1^—¦C can reduce sperm count and sperm quality, so men concerned about fertility are cautioned to avoid too much time in the hot tub or sauna. A new study suggests that men also keep their laptop computers off their laps. The study measured scrotal temperature in 29 healthy male volunteers as they sat with legs together and a laptop computer on the lap. Temperature increase in the left scrotum over a 60-minute session is given as 2.31 ± 0.96 and a note tells us that €˜€˜Temperatures are given as —¦C; values are shown as mean ± SD.€ The abbreviation SD stands for standard deviation. (Men who sit with their legs together without a laptop computer do not show an increase in temperature.)

Transcribed Image Text:

Condition Mean Std.Dev. п Legs together Lap pad Legs apart 29 2.31 0.96 29 2.18 0.69 1.41 29 0.66