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?

Short answer

The practical difficulty is:

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

Step-by-step solution

Given Information

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

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.