Regarding the pooled and nonpooled t-procedures,
a. What is the difference in assumptions between the two procedures?
b. How important is the assumption of independent simple random samples for these procedures?
c. How important is the normality assumption for these procedures?
d. Suppose that the variable under consideration is normally distributed on each of the two populations and that you are going to use independent simple random samples to compare the population means. Fill in the blank and explain your answer:
Unless you are quite sure that the are equal, the nonpooled t-procedures should be used instead of the pooled t-procedures.