Explain the discrepancy - please help

[SavedByNazar]

Hi - I am having such a tough time understanding the solution to this problem. I understand why the wrong answers are wrong, but can't seems to grasp why C is the right answer. Please could anyone help break it down for me? Thank you so much ahead for your help.


In a recent poll, 71% of respondents reported that they cast votes in the most recent national election. Voting records show, however, that only 60% of eligible voters actually voted in that election.

Which of the following pieces of evidence, if true, would provide the best explanation for the discrepancy?

A. The margin of error for the survey was plus or minus five percentage points
B. Fifteen percent of the survey's respondents were living overseas at the time of the election
C. Prior research has show that people who actually do not vote are also more likely to respond to poll than those who do not vote
D. Some people who intend to vote are prevented from doing so by last-minute conflicts on election day or other complications
E. People are less likely to respond to voting poll on the same day that they voted

[Brent@GMATPrepNow]

In a recent poll, 71% of respondents reported that they cast votes in the most recent national election. Voting records show, however, that only 60% of eligible voters actually voted in that election.

Which of the following pieces of evidence, if true, would provide the best explanation for the discrepancy?

A. The margin of error for the survey was plus or minus five percentage points
B. Fifteen percent of the survey's respondents were living overseas at the time of the election
C. Prior research has show that people who actually do not vote are also more likely to respond to poll than those who do not vote
D. Some people who intend to vote are prevented from doing so by last-minute conflicts on election day or other complications
E. People are less likely to respond to voting poll on the same day that they voted

So, the poll numbers (71% voted) do not match up with the actual numbers (60% voted). Why is this?
When we have statistical questions based on samples, we should ALWAYS ask: "Is the sample representative of the entire population?"
For this question, there are two possibilities:
1) The sample IS representative of the population, but several of the poll respondents lied (i.e., they said they voted when they did not vote)
2) The sample is NOT representative of the population.

Answer choice C suggests that the sample is NOT representative of the population. Here we see that the poll respondents may have included a disproportionate number of non-voters.

Of course, you might then ask, "if the poll respondents included a disproportionate number of non-voters" then the poll results should have been WAY LESS THAN 71%. That's where we get into the lying scenario. It looks like non-voters may be predisposed to lying about whether or not they voted, and this explains why the poll voting numbers were so much higher than the actual voting numbers.

Cheers,
Brent

[SavedByNazar]

Thank You SO MUCH! After reading several explanations, the one you've provided below was as clear as water. Appreciate the help again a ton!

In a recent poll, 71% of respondents reported that they cast votes in the most recent national election. Voting records show, however, that only 60% of eligible voters actually voted in that election.

Which of the following pieces of evidence, if true, would provide the best explanation for the discrepancy?

A. The margin of error for the survey was plus or minus five percentage points
B. Fifteen percent of the survey's respondents were living overseas at the time of the election
C. Prior research has show that people who actually do not vote are also more likely to respond to poll than those who do not vote
D. Some people who intend to vote are prevented from doing so by last-minute conflicts on election day or other complications
E. People are less likely to respond to voting poll on the same day that they voted

So, the poll numbers (71% voted) do not match up with the actual numbers (60% voted). Why is this?
When we have statistical questions based on samples, we should ALWAYS ask: "Is the sample representative of the entire population?"
For this question, there are two possibilities:
1) The sample IS representative of the population, but several of the poll respondents lied (i.e., they said they voted when they did not vote)
2) The sample is NOT representative of the population.

Answer choice C suggests that the sample is NOT representative of the population. Here we see that the poll respondents may have included a disproportionate number of non-voters.

Of course, you might then ask, "if the poll respondents included a disproportionate number of non-voters" then the poll results should have been WAY LESS THAN 71%. That's where we get into the lying scenario. It looks like non-voters may be predisposed to lying about whether or not they voted, and this explains why the poll voting numbers were so much higher than the actual voting numbers.

Cheers,
Brent

[binit]

C. Prior research has show that people who actually do not vote are also more likely to respond to poll than those who do not vote

Hi SavedByNazar,

Although this is a very old post and the Q is perfectly solvable (by elimination) I have serious doubts about the wording in choice C. Can somebody confirm this?

~Binit.