Wording of Polls
A poll in California (done by the Public Policy Institute) asked whether the government should regulate greenhouse gases, and 751 out of 1138 likely voters said yes.
However, when a different polling agency asked whether stricter environmental controls are worth the cost, 523 of 1138 likely voters said yes; the alternative was that the laws hurt the economy and cost too many jobs. (Source: Ventura County Star, March 21, 2013)
a. Find both sample proportions and compare them. Comment on the similarities of the two questions.
b. Determine whether the two sample proportions are significantly different at a 0.05 significance level. Comment on the effect of changing the wording of this question.
c. Using methods learned in Chapter 7, find a 95% confidence interval for the difference between the two percentages, and interpret it. Does it capture 0? What does that mean?