The findings of recent research indicate that prolonged exposure...

Question

The findings of recent research indicate that prolonged exposure to radiation from computer monitors diminishes mental capacity. The evidence cited in the study shows that workers who spend in excess of 20 hours per week directly in front of a computer monitor exhibit an average 12% reduction in cognitive abilities after 15 years in the same occupation.

The response to which of the following questions would be most helpful in evaluating the reasoning presented in the survey?

(A) Was the exhibited decline in cognitive abilities permanent or reversible?
(B) What was the reason for analyzing a 15 year period instead of a 12 or 18 year period?
(C) Did workers performing varying occupational tasks exhibit different reductions in mental capacity?
(D) Did the cognitive abilities of some of the workers decline by less than 12% over the course of the study?
(E) By what percent do the cognitive abilities of the average worker decline over a 15 year period?

AaronPond · Accepted Answer

This is a “Useful to Evaluate” question, which borrows many tactics from traditional Strengthen/Weaken questions. (The leverage phrase in the question stem, “which… would be most helpful in evaluating…” clearly indicates this question type.) With Useful to Evaluate questions, "Minding the Gap" is critical. The correct answer will either plug the gap (Strengthen) or explode the gap (Weaken). Trap answers will not address the logical gap.

The primary logical gap in this question is the disconnect between the data and the conclusion. While the data tells us that workers who spend 20+ hours in front of a computer monitor exhibit a 12% reduction in cognitive abilities after 15 years, we don’t know if that 12% reduction is actually caused by the exposure or if it might be caused by something else during those 15 years. (For example, what if most people who sit at a job for 15 years see a much greater decline in cognitive ability? A mere 12% reduction could actually show that sitting in front of computer monitors keep your brain relatively sharp! Alternatively, what if it isn’t the radiation that causes the decline; instead, sitting in one position for 15 years is what actually causes it?) We need to find the answer choice that addresses this gap in some way.

Answer choice A “moves the goalposts” on the reader, getting the reader to think that the reversibility (or permanency) of the damage matters. This introduces an emotional, human component to the story, but one that isn’t related to the logical gap. A is a trap answer.

Answer choice B traps those who misunderstand what the problem is asking. While questioning the 15-year period might be interesting if someone is evaluating the study as a whole, the question stem explicitly asks us to identify the question that can best help us evaluate the specific reasoning presented. Answer choice B does not address the logical gap between the data and the conclusion.

At first glance, answer choice C looks like it helps us to compare the rates of cognitive decline across a spectrum of various occupational tasks. However, answer choice C is a Yes/No question that doesn’t really help us much: if the answer is “No”, then it appears that occupational tasks might not determine cognitive decline. But if we answer “Yes”, then we only know that there   is   a relationship between occupational tasks and cognitive decline. We don’t know   what   that relationship is, and we have no data points to compare. Answer choice C gets us started, but is very  weak .

Answer choice D doesn’t mind the logical gap. In fact, the problem states that the “average” cognitive decline was 12%. This data point implies that either (1) all of the participants somehow had the exact same 12% drop, or (2) some people were above and others were below the 12% average. That is how “average” works. It is very likely that the data was spread around the 12% average, so D tells us very little. And D certainly doesn’t address the lack of clear causal link between monitor exposure and cognitive decline.

Answer choice E gives us a strong comparative that can help us prove (or disprove) a potential causal link. The answer to the question in this answer choice would give us a measurable number against which we can compare the 12% cognitive decline. Whether the cognitive decline rate of the average worker is higher than, lower than, or equal to the measured 12% decline, such data could give us strong leverage to evaluate the reasoning in the argument.   Answer choice E is the correct answer.

techiesam · Answer

AaronPond

Sir,
With all due respect,I would like to point out that you have posted the question on 21:29 and posted the OE at 21:33.At least give people some time to give their point of view.Then you can step in whenever you want.
Its a good question by the way.

tulikasaxena01 · Answer

Was confused b/w C and E
I chose C : since it states the relationship b/w type of occupation and cognitive ability .
Don't understand why E is correct ?

Please help!

Temurkhon · Answer

in fact, all options are not good.

Ideally, we need information saying what is percentage
of reducing capacity in people who use comp less than 20 hours. 
Option E does not answer that question because "average user" can still use 20 hours

AaronPond · Answer

To be more specific, I would argue that "all options are not perfect ." But questions such as as these are not asking you to find the ultimate answer that plugs the logic so perfectly Aristotle himself rises from the grave and applauds you for the answer. It is easy to overthink such questions if you are looking for a perfect solution that matches all your preconceived notions. The problem simply asks, " The response to which of the following questions would be most helpful in evaluating the reasoning presented in the survey? " "Most helpful" doesn't mean flawless. This highlights a common trap of the GMAT which I call " Directional Nudges " in my classes. You need to find the answer that best does the job. Answer choice E does exactly that. Yes, the "average user" could still "use 20 hours", but because average (by definition) aggregates ALL users (including, but not limited to, the ones discussed in the research), answer choice E provides a comparative. We just are trying to determine whether prolonged exposure to radiation from computer monitors " diminishes " mental capacity. Since the research seems to separate out users that worked " in excess of 20 hours per week ", this means it left out of its total all those who worked below that level. On the other hand, an "average" would include those who worked below that level. It helps us to see if the "heavily irradiated" folks are comparably different to the "slightly irradiated" folks, without knowing specifics. It may be also worth noting for some of you studying for the GMAT that "Useful to Evaluate" questions can stop short of actually giving new data that actually proves or disproves a fact. The correct answers to such questions simply provide a future direction for research or additional possibilities that, if known, would help us make a conclusion one way or the other. Answer E suggests the possible usefulness of knowing a comparative average percentage. Such information would allow us to conclude exactly what the question is asking: what information would help us prove (or disprove) whether "prolonged exposure" (arguably somewhere in the 20+ hours range) "diminishes" mental capacity. We don't need to know the numbers to answer the question. Hypothetically, if average mental decline over 15 years were 5%, then we would know that heavily irradiated folks seem to decline faster on average. If the same mental decline was 12%, we might suspect that monitor use had little effect. If the same average mental decline were 20%, this would hint that staring at computer screens all day might even be good for us. But don't stare at this screen for too long, or you might overthink the question.

No matter if the average turned out to be 5%, or 12%, or 20%, any of those measures would be " helpful in evaluating the reasoning ." The answer is definitely E .

DrHuber · Answer

The most helpful question for evaluating the reasoning presented in the survey would be:

(E) By what percent do the cognitive abilities of the average worker decline over a 15-year period?

This question directly addresses the findings mentioned in the survey and seeks to understand the extent of cognitive decline experienced by the average worker over the specified time period. It provides crucial information to assess the significance of the reported 12% reduction in cognitive abilities after 15 years. By knowing the average decline, one can better evaluate the impact of prolonged exposure to computer monitors on mental capacity.

shaishav.53 · Answer

The data presented is quite clear that those using computers more than 20 hours per week, sitting directly in front of a computer monitor  exhibit  an average 12% reduction in cognitive abilities after 15 years  in the same occupation .

The conclusion is "The findings of recent research indicate that  prolonged  exposure to radiation from computer monitors diminishes mental capacity".... Perfect..

I don't know how (E) helps further in evaluating this conclusion. Rather to firm in my belief in the conclusion one would like to know why the study chose a period of 15 years and not more or less. That can actually define the prolonged in the conclusion. Hence, i would chose option (B)...

Rest all the options are frankly given in the question stem and why do we need them.

Views please?

Haffun · Answer

I think this is a high quality question with a high quality explanation by AaronPond. There's a lot of contention on the answer choice, but E seems to be the best answer after reading Aaron's post.
Initially I thought the avg worker is from the same population of workers that showed 12% reduction in Cognitive abilities(CA).

In (E), the avg worker is not only the worker that has 20+ hours of exposure to computer but also that that does not have such a prolonged exposure, i.e. representative of the work force not limited to using computers for 20+hrs. Thus, knowing the % decline in CA of an avg worker in 15 years will certainly help evaluate whether the conclusion is correct.
Beautiful question!

Dooperman · Answer

(A) Was the exhibited decline in cognitive abilities permanent or reversible?
We are comparing the decline after 15 years. This option doesn't affect the argument.

(B) What was the reason for analyzing a 15 year period instead of a 12 or 18 year period?
Again argument is about results after 15 years. So option also doesn't affect the argument.

(C) Did workers performing varying occupational tasks exhibit different reductions in mental capacity?
Hold On.

(D) Did the cognitive abilities of some of the workers decline by less than 12% over the course of the study?
Passage says average reduction. Hence this doesn't change anything.

(E) By what percent do the cognitive abilities of the average worker decline over a 15 year period?
Hold on.

C Vs E
E talks about decline of an average worker (no matter what job you do). The answer to this question would help substantiate the argument. Hence E make a lot more sense.

VerbalBot · Answer

Automated notice from GMAT Club VerbalBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

The findings of recent research indicate that prolonged exposure...

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Critical Reasoning (CR) Questions

The findings of recent research indicate that prolonged exposure...

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards