Q. 14 - The Practice of Statistics for AP

Question

Refer to Exercise $12$. As Gallup indicates, the $3$ percentage point margin of error for this poll includes only sampling variability (what they call “sampling error”). What other potential sources of error (Gallup calls these “non-sampling errors”) could affect the accuracy of the $59\%$ estimate? 

Step-by-Step Solution

Answer

The practical difficulty is:

Nonresponse bias is the result of not having data for everybody in the sample.

Step 1: Given Information

As Gallup indicates, the $3$ percentage point margin of error for this poll includes only sampling variability 

Step 2: Explanation

Some of the practical difficulties:

Selection bias will exclude part of the population

Measurement of response bias will use a method that gives different values from the true value

Nonresponse bias is the result of not having data for everybody in the sample.