Question
AP Statistics Unit 12 Inference for Proportions Free Response Directions: Complete the assignment on this paper. Your answers for this assignment must include reasons; simply
APStatistics
Unit 12
Inference for Proportions
Free Response
Directions: Complete the assignment on this paper. Your answers for this assignment must include reasons; simply stating the answer without justification will earn partial credit.
- Political parties rely heavily upon polling to measure their support in the electorate.Below are the results of two polls conducted in 1996 and 1997 for four political parties.
- The polling organization selects people to participate in the poll using random-digit dialing and then uses some procedure to randomly select a member of the household called. Why doesn't the polling organization just ask people in the nearest shopping center? (4 points)
- Compute the estimated standard error for the level of support of the L party in 1996. Interpret this value. (4 points)
- Construct an approximate 95% confidence interval for the level of support for the N party in 1996. Interpret this interval. (4 points)
- Has the level of support for the R party changed between 1996 and 1997? Create a 95% confidence for both 1996 and 1997 for the R party. Use any summary statistics, intervals, or graphs that are appropriate. (4 points)
- The 1996 poll interviewed 1183 people in Canada and gave a certain level of precision as shown above. What sample sizes would be required for polls in the United States (population 10 times larger) to give the same level of precision? Explain. (4 points)
- This is an actual query received from a statistical consulting service.
"Can you answer a question for us regarding percentage of returns? If a survey was mailed to 4,000 households asking three simple questions and included a postage-paid return postcard, how many responses would be considered representative? Any guidance you could give would be appreciated."
How would you respond to this query? (4 points)
- A survey of tobacco use in high schools tested the saliva of female and male students for presence of tobacco byproducts. Three-hundred eighteen (318) randomly selected females participated in the study, as did 336 randomly selected males. Cross-tabulated data are shown in the table below.
TABLE: Data from tobacco survey
Tobacco +
Tobacco -
Female
39
279
Male
26
310
- Calculate the proportion of tobacco use in female subjects and in male subjects. Discuss your findings. (6 points)
- Test the proportions for a significant difference in tobacco use between males and females. Let ? = .05. Show all work including statement of Ho (and so on). Discuss your findings. (12 points)
- A random sample of 262 leukemia cases shows that 150 are male and 112 are female. Therefore, the observed proportion of cases that are male = 150 / (150 + 112) = .5725. If there were no gender preference for this disease, we would expect 50% of cases to be male. Is the observed proportion significantly different from expected? Let a = .05. Show all hypothesis testing steps, and interpret your results. (10 points)
APStatistics Unit 12 Inference for Proportions Free Response Directions: Complete the assignment on this paper. Your answers for this assignment must include reasons; simply stating the answer without justification will earn partial credit. 1. Political parties rely heavily upon polling to measure their support in the electorate. Below are the results of two polls conducted in 1996 and 1997 for four political parties. a. The polling organization selects people to participate in the poll using randomdigit dialing and then uses some procedure to randomly select a member of the household called. Why doesn't the polling organization just ask people in the nearest shopping center? (4 points) b. Compute the estimated standard error for the level of support of the L party in 1996. Interpret this value. (4 points) c. Construct an approximate 95% confidence interval for the level of support for the N party in 1996. Interpret this interval. (4 points) d. Has the level of support for the R party changed between 1996 and 1997? Create a 95% confidence for both 1996 and 1997 for the R party. Use any summary statistics, intervals, or graphs that are appropriate. (4 points) e. The 1996 poll interviewed 1183 people in Canada and gave a certain level of precision as shown above. What sample sizes would be required for polls in the United States (population 10 times larger) to give the same level of precision? Explain. (4 points) f. This is an actual query received from a statistical consulting service. "Can you answer a question for us regarding percentage of returns? If a survey was mailed to 4,000 households asking three simple questions and included a postagepaid return postcard, how many responses would be considered representative? Any guidance you could give would be appreciated." How would you respond to this query? (4 points) 2. A survey of tobacco use in high schools tested the saliva of female and male students for presence of tobacco byproducts. Threehundred eighteen (318) randomly selected females participated in the study, as did 336 randomly selected males. Crosstabulated data are shown in the table below. TABLE: Data from tobacco survey Female Male Tobacco + 39 26 Tobacco 279 310 a. Calculate the proportion of tobacco use in female subjects and in male subjects. Discuss your findings. (6 points) b. Test the proportions for a significant difference in tobacco use between males and females. Let = .05. Show all work including statement of Ho (and so on). Discuss your findings. (12 points) 3. A random sample of 262 leukemia cases shows that 150 are male and 112 are female. Therefore, the observed proportion of cases that are male = 150 / (150 + 112) = .5725. If there were no gender preference for this disease, we would expect 50% of cases to be male. Is the observed proportion significantly different from expected? Let = .05. Show all hypothesis testing steps, and interpret your results. (10 points)
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