Statistics Problem~~~~

2008-03-30 5:58 pm

A random sample of 415 potential voters was interviewed 3 weeks before the start of a state wide campaign for governor; 223 of the 415 said they favored the new candidate over the incumbent. However, the new candidate made several unfortunate remarks one week before election. Subsequently, a new random sample of 630 potential voters showed that 317 voters favored the new candidate.

Do these data support the conclusion that there was a decrease in voter support for the new candidate after the unfortunate remarks were made? Give appropriate statistical evidence to support your answer.

回答 (1)

myisland8132

2008-04-04 8:02 am

✔ 最佳答案

p1=223/415=0.5373
p2=317/630=0.5032

H0:p2>=p1
H1:H0 is not true

pi hat=(223+317)/(415+630)=540/1045=0.5167

z
=(0.5032-0.5373)/sqrt[(0.5167)(0.4833)(1/415+1/630)]
=-0.0341/(0.03159)
=-1.0794

alpha=0.1, critical value=-1.28

Since Z>-1.28

So do not reject H0 and conclude that there was no decrease in voter support for the new candidate after the unfortunate remarks were made

2008-04-04 00:03:09 補充：
&gt >

參考: http://www.cliffsnotes.com/WileyCDA/CliffsReviewTopic/Test-for-Comparing-Two-Proportions.topicArticleId-25951,articleId-25942.html

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