Understanding Basic Statistics 6th Edition by Charles Henry Brase,Corrinne Pellillo Brase

Exercise 22

Critical Thinking Josh and Kendra each calculated a 90% confidence interval for the difference of means using a Student's t distribution for random sam­ples of size n 1 = 20 and n 2 = 31. Kendra followed the convention of using the smaller sample size to compute d.f. = 19. Josh used his calculator and Satterthwaite's approximation and obtained d.f. 36.3. Which confidence interval is shorter Which confidence interval is more conservative in the sense that the margin of error is larger