91Ó°ÊÓ

Explain the difference between the observed and expected frequencies for a goodness-of-fit test.

How is the expected frequency of a category calculated for a goodness-of-fit test? What are the degrees of freedom for such a test?

Explain how the expected frequencies for cells of a contingency table are calculated in a test of independence or homogeneity. How do you find the degrees of freedom for such tests?

A sample of 25 observations selected from a normally distributed population produced a sample variance of 35 . Construct a confidence interval for \(\sigma^{2}\) for each of the following confidence levels and comment on what happens to the confidence interval of \(\sigma^{2}\) when the confidence level decreases. a. \(1-\alpha=.99\) b. \(1-\alpha=.95\) c. \(1-\alpha=.90\)