Does heavy cell phone use affect brain activity? There is some concern about pos
ID: 3328756 • Letter: D
Question
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,1 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.
(b) The investigators were interested in seeing whether average brain glucose metabolism was different based on whether the cell phones were turned on or off.
State the null and alternative hypotheses for this test.
Let group 1 be when the cell phones are on, and let group 2 be when the cell phones are off.
(e) State the null and alternative hypotheses for the test in part (d).
(c) The p-value for the test in part (b) is 0.004. State the conclusion of this test in context. There is evidence that the radiofrequency waves from cell phones affect brain activity There is evidence that radiofrequency waves from cell phones do not affect brain activity. There is no evidence that radiofrequency waves from cell phones affect brain activity Reject Ho O Do not reject Ho .Explanation / Answer
Sorry, but part (a) is not provided -- > Hence starting from (b)
(b)Let a1 and a2 be the average brain glucose metabolism in the ON state and OFF state respectively, then the Null hypotheses under test is H0: a1 = a2 against the alternative hypotheses H1 : a1 not equal to a2.
(c) The p-value is 0.004 < 0.01 (if level of significance is 0.01 then we reject H0 if p-value < 0.01). Hence here we Reject H0. Answer is Reject H0.
(d) To study if there is any correlation between the amplitude of radio frequency waves and the glucose metabolism, we must plot a SCATTERPLOT (ans). Because by looking at the structure of the scatterplot we will be able to say if the metabolism decreases with higher amplitude or not.
(e) If p be the correlation parameter between the amplitude and the glucose metabolism then the hypotheses under test is H0:p=0 against the alternative hypotheses H1:p not equal to 0 .
(f) Using same logic as mentioned in (c), since p-value < 0.001 hence we reject H0.
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