1. A 2012 Gallup survey of a random sample of 1014 American adults indicates that American families spend, on average, $151 per week on food. The report further states that, with 95% confidence, this estimate has a margin of error of ±$7.

a) This confidence interval is expressed in the following form: “estimate ± margin of error.” What is the range of values (lower bound, upper bound) that corresponds to this confidence interval?

b) What is the parameter captured by this confidence interval? What does it mean to say that we have “95% confidence” in this interval?

1. Explain whether the confidence interval cited accounts for the following sources of error. 
2. i)The poll dialed telephone numbers at random and so missed all people without phones.

ii) Nonresponse—some people whose phone numbers were chosen never answered the phone in several calls or answered but refused to participate in the poll.

iii) There is chance variation in the random selection of telephone numbers.

iv) Respondents may not accurately assess how much they spend on food or may not answer truthfully.

Answer rating: 100% (QA)

a The range of values according to the confidence interval is as follows lower bound 1517144 Upper b... View the full answer