When getting voters to support a candidate in an election, is there a difference between a recorded phone call from the candidate or a flyer about the candidate sent through the mail? A sample of 400 voters is randomly divided into two groups of 200 each, with one group getting the phone call and one group getting the flyer. The voters are then contacted to see if the plan to vote for the candidate in questions. We wish to see if there is evidence that the proportions of support are different between the two methods of campaigning.

Sample A

Will vote for Candidate

Will not vote for Candidate

Phone Call

118

92

Flyer

102

98

Table 1: Sample A: is a phone call or a flyer more effective?

Sample B

Will vote for Candidate

Will not vote for Candidate

Phone Call

183

17

Flyer

141

59

Table 2: Sample B: is a phone call or a flyer more effective?

a) State the null and alternative hypotheses. Be sure to use the correct notation.

Let group 1 be the supporters of Candidate A after a phone call and let group 2 be the supporters of Candidate A after a flyer.

Ho: vs Ha:

b). Possible sample results are shown in Table 1.

Compute the two sample proportions: , the proportion of voters getting the phone call who say they will vote for the candidate, and , the proportions of voters getting the flyer who say they will vote for the candidate. Enter the exact answers.

=

=

Is there a difference in the sample proportions? Yes or No

c). A different set of possible sample results are shown in Table 2.

Compute the same two sample proportions for this table. Enter exact answers.

=

=

d). Which of the two samples seems to offer stronger evidence of a difference in effectiveness between the two campaign methods?

a. Sample A

b. Sample B

Answer:

2. The null and alternative hypotheses for a test are given, as well as some information about the actual sample and t he statistic that is computed for each randomization sample. Indicate where the randomization distribution will be centered.

Ho: vs Ha: Sample: Randomization statistic:

Centered: