1. What is the population of interest? What is the sampled population? Are these two populations the same? If the sampled population is only a subset of the population of interest, undercoverage limits our ability to generalize to the population of interest. For example, if the population of interest is all students at a particular university, but the sample is selected from only those students who choose to list their phone number in the campus directory, undercoverage may be a problem.

We would need to think carefully about whether it is reasonable to consider the sample as representative of the population of all students at the university.

Overcoverage results when the sampled population is actually larger than the population of interest. This would be the case if we were interested in the population of all high schools that offer Advanced Placement (AP) Statistics but sampled from a list of all schools that offered an AP class in any subject. Both undercoverage and overcoverage can be problematic.