For Exercises 8.1 and 8.2, see page 419; for 8.3 and 8.4, see page 421; for 8.5 to 8.7, see page 423; for 8.8 to 8.11, see pages 425–426; for 8.12, see page 426; for 8.13 and 8.14, see page 429; and for 8.15 and 8.16, see page 431.

Question 8.11

8.11 The effect of

In Example 8.4, consider what would have happened if you had paid for 40 subjects to be tested. Assume that the results would be the same as what you obtained for 20 subjects; that is, 65% had better UVA and UVB protection with your product.

  1. Perform the significance test and summarize the results.
  2. Compare these results with those you found in the previous exercise, and write a short summary of the effect of the sample size on these significance tests.

8.11

(a) . The data do not show a significant difference between your product and your competitor’s. (b) As the sample size increases, the test statistic increases and the -value gets smaller, making the data more significant. So while we didn’t get significance at the 5% level, the data are more significant with the larger sample size.