Discussion Questions:

1. Explain the difference between an independent and dependent sample.
2. A stock analyst wants to know if there is a difference between the mean rate of return from energy stocks and that from financial stocks. He randomly selects13energy stocks and computes the rate of return for the past year. He randomly selects13financial stocks and computes the rate of return for the past year. Is the sampling method dependent or independent? Why? Is the response variable quantitative or qualitative?
3. Why do we use a pooled estimate of the population proportion when testing a hypothesis about two proportions? Why do we not use a pooled estimate of the population proportion when constructing a confidence interval for the difference of two proportion?