(22.25) The Harris Poll asked a sample of smokers, Do you believe that smoking w
ID: 3232353 • Letter: #
Question
(22.25) The Harris Poll asked a sample of smokers, Do you believe that smoking will probably shorten your life, or not?
Of the 1010 people in the sample, 848 said Yes.
Step 1:
Harris called residential telephone numbers at random in an attempt to contact an SRS of smokers.
Based on what you know about national sample surveys, what is likely to be the biggest weakness in the survey?
People are suspicious when they are asked over the phone, because they are not sure about the identity of the caller.
This may result in insincere answers.
Step 2:
We will nonetheless act as if the people interviewed are an SRS of smokers.
Give a 95% four plus confidence interval for the percent of smokers who agree that smoking will probably shorten their lives.
People are suspicious when they are asked over the phone, because they are not sure about the identity of the caller.
This may result in insincere answers.
Step 2:
We will nonetheless act as if the people interviewed are an SRS of smokers.
Give a 95% four plus confidence interval for the percent of smokers who agree that smoking will probably shorten their lives.
Explanation / Answer
Step 1:
Harris called residential telephone numbers at random in an attempt to contact an SRS of smokers.
Based on what you know about national sample surveys, what is likely to be the biggest weakness in the survey
The answers may be influenced by the formulation of the question
step 2)
for p=845/1010 =0.84 ; p=1010
std error of mean =(p(!-p)/n)1/2 =0.0115
for 95% CI, z=1.96
hence confidence interval =p-/+z*std error =0.8170 to 0.8622
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