In: Statistics and Probability
3.3 What is the effect of concussion on brain size? Researchers
measured the brain sizes (hippocampal volume in
microliters) of 25 football players with a history of medically
diagnosed concussion and 25 football player who
did not have any history of concussion.
The data are summarised below.
Group | Mean | Std. Deviation |
concussion | 5819 | 597.2 |
Non-concussion | 6377 | 709.8 |
a) Are the mean brain sizes for footballers from the two
concussion groups significantly different?
Carry out a hypothesis test. Use a significance level of 5% and use
df = n1+n2-2.
b) Create a 95% confidence interval for the mean difference in
brain size, and interpret the interval.
c) Does the confidence interval confirm your answer to a)?
Explain.