Exercise 4.86 on page 263 introduces a matched pairs study in which 47 participants had cell phones put on their ears and then had their brain glucose metabolism (a measure of brain activity) measured under two conditions: with one cell phone turned on for 50 minutes (the ‘‘on” condition) and with both cell phones off (the ‘‘off” condition). Brain glucose metabolism is measured in μ mol/100 g per minute, and the differences of the metabolism rate in the on condition minus the metabolism rate in the off condition were computed for all participants. The mean of the differences was 2.4 with a standard deviation of 6.3. Find and interpret a 95% confidence interval for the effect size of the cell phone waves on mean brain metabolism rate.  

Exercise 4.86 on page 263

Does heavy cell phone use affect brain activity? There is some concern about possible negative effects of radiofrequency signals delivered to the brain. In a randomized matched-pairs study 47 healthy participants had cell phones placed on the left and right ears. Brain glucose metabolism (a measure of brain activity) was measured for all participants under two conditions: with one cell phone turned on for 50 minutes (the ‘‘on” condition) and with both cell phones off (the ‘‘off” condition). The amplitude of radiofrequency waves emitted by the cell phones during the ‘‘on” condition was also measured.