broall wrote:
A medical journal used a questionnaire survey to determine whether a particular change in its format would increase its readership. Sixty-two percent of those who returned the questionnaire supported that change. On the basis of this outcome, the decision was made to introduce the new format.
Which one of the following, if it were determined to be true, would provide the best evidence that the journal's decision will have the desired effect?
(A) Of the readers who received questionnires, 90 percent returned them.
(B) Other journals have based format changes on survey results.
(C) The percentage of surveyed readers who like the format change was almost the same as the percentage of the entire potential readership who would like format change.
(D) It was determined that the new format would be less costly than the old format.
(E) Ninety percent of the readers who were dissatisfied with the old format and only 50 percent of the readers who like the old format returned their questionnaires.
Source: LSAT
The magazine sent a survey to its readers.
Of those who answered back (survey participants), 62% supported the change.
Magazine decided to implement the change.
So based on the opinion of a sample, the magazine assumed that the opinion among the population will be the same and hence decided to implement the change. We need to support this line of thinking which means we need to give some data that supports that the sample does represent the population.
(A) Of the readers who received questionnires, 90 percent returned them.
This option tells us that 90% of the magazine's readership was the sample size i.e. 90% people participated in the survey. Now think about this - does it matter whether 90% participates or 80% participate or 40% participated? The number of people that participated are our sample. We don't know whether the absolute number is large or small. If the magazine's readership has very few people, 90% may be a small sample size. If the magazine has a large readership base, 40% may be a large enough sample size too.
So this option doesn't really provide any support to the authenticity of the survey result.
(B) Other journals have based format changes on survey results.
Irrelevant. We don't know whether the journals were similar and whether their decisions turned out to be suitable.
(C) The percentage of surveyed readers who like the format change was almost the same as the percentage of the entire potential readership who would like format change.
Correct. This says that the sample was an accurate representation of the entire population. If that is the case, then we can expect 62% of the entire potential readership to like the change. It certainly sounds good for the plan.
(D) It was determined that the new format would be less costly than the old format.
Cost is not being discussed here. We are discussing increase in readership.
(E) Ninety percent of the readers who were dissatisfied with the old format and only 50 percent of the readers who like the old format returned their questionnaires.
This weakens the result of the survey and is hence not the answer.
Assuming 100 people responded to the survey, 62 liked the new format while 38 liked the old format.
This option (E) tells us that the 38 people who liked the old format were only 50% of the total who liked the old format. So actually 76 people liked the old format.
Also it tells us that the 62 people who liked the new format were 90% of all total who liked the new format so about 69 people liked the new format.
Hence, in reality more people liked the old format better and the change may not be good for the magazine. Just that fewer people who liked the old format responded.
Answer (C)