The NCAA is interested in estimating the difference in mean number of daily trai
ID: 3024174 • Letter: T
Question
The NCAA is interested in estimating the difference in mean number of daily training hours for men and women athletes on college campuses. They want 95 percent confidence and will select a sample of 10 men and 10 women for the study. If the NCAA assumes that the population standard deviations are known, the critical value for the confidence interval is t = 2.1009.
TRUE or FALSE.
(I know the answer is false but i am not sure why. Looking on the t table at the df you go to 18 and 95% confidence which means that it would be t=2.1009. I must be missing something as to why it is false.)
Explanation / Answer
Hi! There are many conventions in which the degrees of freedom is solved for for 2 independent groups.
1. If could be df = n1 + n2 - 2. However, in this case, it would have been true if you use this.
2. Using the lower value between n1 - 1 and n2 - 1. In that case, df = 9 here, so it is false.
3. Using technology. These are called "ugly degrees of freedom" sometimes, because it has decimals.
So maybe you were expected to use either 2 or 3.
Another possibility is that you are expected to use z instead of t, because the population standard deviation is known, although I doubt it because of the small sample size.
Thanks!