A recent study1 examined the relationship of football and concussions on hippocampus volume in the brain. The study included three groups with n=25 in each group: healthy controls who had never played football, football players with no history of concussions, and football players with a history of concussions. In this exercise, we test for evidence that average brain size is larger in football players who have never had a concussion (FBNoConcuss) than in football players with a history of concussions (FBConcuss). The data are in FootballBrain where the variable Hipp measures brain size as the volume of the hippocampus (in ml) for each subject.
Let group 1 be the football players with no concussion and group 2 be the football players with a history of concussions.
(a) State the null and alternative hypotheses.
(b) Use StatKey or other technology to find the value of the relevant sample statistic. Round your answer to one decimal place.
(c) Use StatKey or other technology to find the p-value. Round your answer to three decimal places.
(d) Does it appear that this difference in brain size is just due to random chance?