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3965and4835 slide 33 howabout

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Unformatted text preview: 2000 p ± zα / 2 p (1 − p ) / n = 0.113 ±1.96 .113(1 − .113) / 2000 i.e. 0.113 ± .014 Slide 30 Interval Estimation of a Population Proportion s Solution Viewers Sample Proportion Observations LCL UCL 0.113 2000 0.099 0.127 Interpretation: We have 95% confidence that the number of viewers who watched the Tonight Show is in between.099(100 million)= 9.9 million and 127(100 million)=12.7 million Slide 31 Interval Estimation of a Population Proportion s Another Example: Political Science, Inc. Political Science, Inc. (PSI) specializes in voter polls and surveys designed to keep political office seekers informed of their position in a race. Using telephone surveys, interviewers ask registered voters who they would vote for if the election were held that day. In a recent election campaign, PSI found that 220 registered voters, out of 500 contacted, favored a particular party. PSI wants to develop a 95% confidence interval estimate for the proportion of the population of registered voters that favors the party. Slide 32 Interval Estimation of a Population Proportion s Another Example: Political Science, Inc. We have: n = 500, p = 220/500 = .44, zα/2 = 1.96 p ± zα / 2 p (1 − p ) / n = 0.44 ±1.96 .44(1 − .44) / 500 i.e. 0.44 ± .0435 PSI is 95% confident that the proportion of all voters that favors the party is between .3965 and .4835. Slide 33 How about……… …if the sample size is small, or any of the requirements i...
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