Question

A study considered the question, "Are you a registered voter?" Accuracy of response was confirmed by a check of city voting records. Two methods of survey were used: a face-to-face interview and a telephone interview. A random sample of 88 people were asked the voter registration question face to face. Of those sampled, seventy-one respondents gave accurate answers (as verified by city records). Another random sample of 90 people were asked the same question during a telephone interview. Of those sampled, seventy-one respondents gave accurate answers. Assume the samples are representative of the general population.

Let p1 be the population proportion of all people who answer the voter registration question accurately during a face-to-face interview. Let p2 be the population proportion of all people who answer the question accurately during a telephone interview. Find a 90% confidence interval for p1 – p2. (Use 3 decimal places.)

lower limit

upper limit

Answer 1

• Let p1 be the population proportion of all people who answer the voter registration question accurately during a face-to-face interview is 0.807.
• Let p2 be the population proportion of all people who answer the question accurately during a telephone interview is 0.789.
• Lower limit =-0.081
• upper limit =0.117