1. P-value. Have harsher penalties and ad campaigns increased seat-belt use among drivers and passengers? Observations of commuter traffic have failed to find evidence of a significant change compared with three years ago. Explain what the study's P-value of 0.17 means in this context.
2. Another P-value. A company developing scanners to search for hidden weapons at airports has concluded that a new device is significantly better than the current scanner. The company made this decision based on a P-value of 0.03. Explain the meaning of the P-value in this context.
3. Ad campaign. An information technology analyst believes that they are losing customers on their website who find the checkout and purchase system too compli- cated. She adds a one-click feature to the website, to make it easier but finds that only about 10% of the customers are using it. She decides to launch an ad awareness campaign to tell customers about the new feature in the hope of increasing the percentage. She doesn't see much of a differ- ence, so she hires a consultant to help her. The consultant selects a random sample of recent purchases, tests the hypothesis that the ads produced no change against the alternative that the percent who use the one-click feature is now greater than 10%, and finds a P-value of 0.22. Which conclusion is appropriate? Explain.
a) There's a 22% chance that the ads worked.
b) There's a 78% chance that the ads worked.
c) There's a 22% chance that the null hypothesis is true.
d) There's a 22% chance that natural sampling variation could produce poll results like these if the use of the oneclick feature has increased.
e) There's a 22% chance that natural sampling variation could produce poll results like these if there's really no change in website use.