Football, Brain Size, and Cognitive Scores Exercise 2.143 on page 102 introduces a study that examines the association between playing football, brain size as measured by left hippocampal volume (in $\mu \mathrm{L}$ ), and percentile on a cognitive reaction test. Figure 2.56 gives two scatterplots. Both have number of years playing football as the explanatory variable while Graph

(a) has cognitive percentile as the response variable and Graph

(b) has hippocampal volume as the response variable.

(a) The two corresponding correlations are -0.465 and -0.366 . Which correlation goes with which scatterplot?

(b) Both correlations are negative. Interpret what this means in terms of football, brain size, and cognitive percentile.

Figure 2.56:

Data From Exercise 2.143:
A recent study examined the relationship of football and concussions on hippocampus volume in the brain. The study included three groups with \(n=25\) in each group: heathy controls who had never played football, football players with no history of concussions, and football players with a history of concussions. Figure 2.41 shows side-by-side boxplots for total hippocampus volume, in \(\mu \mathrm{L}\), for the three groups.

Transcribed Image Text:

100 Cognitive Percentile 20 40 40 20 T 80 60 .. 0 6 8 10 12 14 16 18 Years of Football (a) 4000 3500 Left Hippocampus Volume 3000 T 2500 T 2000 6 8 10 12 .... T 14 16 18 Years of Football (b)