Exercise 4.19 on page 269 describes a study investigating the effects of
exercise on cognitive function. \({ }^{31}\) Separate groups of mice were
exposed to running wheels for \(0,2,4,7,\) or 10 days. Cognitive function was
measured by \(Y\) maze performance. The study was testing whether exercise
improves brain function, whether exercise reduces levels of BMP (a protein
which makes the brain slower and less nimble), and whether exercise increases
the levels of noggin (which improves the brain's ability). For each of the
results quoted in parts (a), (b), and (c), interpret the information about the
p-value in terms of evidence for the effect.
(a) "Exercise improved Y-maze performance in most mice by the 7 th day of
exposure, with further increases after 10 days for all mice tested \((p<.01)\)
(b) "After only two days of running, BMP ... was reduced \(\ldots\) and it
remained decreased for all subsequent time-points \((p<.01)\)."
(c) "Levels of noggin ... did not change until 4 days, but had increased 1.5
-fold by \(7-10\) days of exercise \((p<.001)\)."
(d) Which of the tests appears to show the strongest statistical effect?
(e) What (if anything) can we conclude about the effects of exercise on mice?
