Online bookstore. In Exercise 33 from Chapter 2 you took an SRS of book titles from amazon.com. Use the same book genre for this problem.
a Stratify the population into two categories: hardcover and paperback. You can obtain the population counts in the paperback category by refining your search to include the word paperback.
b Take a stratified random sample of 40 books from your population using proportional allocation. Record the price and number of pages for each book.
c Give a point estimate and a 95% CI for the mean price of books and the mean number of pages for books in the population.
d Compare your CI’s to those from Exercise 33 of Chapter 2. Does stratification appear to increase the precision of your estimate?
e Use your SRS from Chapter 2 to estimate the within-stratum variance of book price for each stratum. In this case, you are using the SRS as a pilot sample to help design a subsequent sample. Find the optimal allocation for a stratified random sample of 40 books. How does the optimal allocation differ from the proportional allocation?
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