In an article in the Journal of Advertising, Weinberger andSpotts compare the use of humor in television ads in the UnitedStates and in the United Kingdom. Suppose that independent randomsamples of television ads are taken in the two countries. A randomsample of 400 television ads in the United Kingdom reveals that 143use humor, while a random sample of 500 television ads in theUnited States reveals that 126 use humor.
(a) Set up the null and alternative hypotheses needed todetermine whether the proportion of ads using humor in the UnitedKingdom differs from the proportion of ads using humor in theUnited States.
(b) Test the hypotheses you set up in part a by using criticalvalues and by setting α equal to .10, .05, .01, and .001. How muchevidence is there that the proportions of U.K. and U.S. ads usinghumor are different? (Round the proportion values to 3 decimalplaces. Round your answer to 2 decimal places.)
(c) Set up the hypotheses needed to attempt to establish thatthe difference between the proportions of U.K. and U.S. ads usinghumor is more than .05 (five percentage points). Test thesehypotheses by using a p-value and by setting α equal to .10, .05,.01, and .001. How much evidence is there that the differencebetween the proportions exceeds .05? (Round the proportion valuesto 3 decimal places. Round your z value to 2 decimal places andp-value to 4 decimal places.) (d) Calculate a 95 percent confidenceinterval for the difference between the proportion of U.K. adsusing humor and the proportion of U.S. ads using humor. Interpretthis interval. Can we be 95 percent confident that the proportionof U.K. ads using humor is greater than the proportion of U.S. adsusing humor? (Round the proportion values to 3 decimal places.Round your answers to 4 decimal places.)
