In response to office workers' worries .....

Question

In response to office workers' worries about the health risks associated with using video display terminals (VDTs), researchers asked office workers to estimate both the amount of time they had spent using VDTs and how often they had suffered headaches over the previous year. According to the survey, frequent VDT users suffered from headaches more often than other office workers did, leading researchers to conclude that VDTs cause headaches.
Which one of the following, if true, most undermines the researchers' conclusion?
(A) Few often office workers surveyed participated in regular health programs during the year in question.
(B) In their study the researchers failed to ask the workers to distinguish between severe migraine headaches and mild headaches. 
(C) Previous studies have shown that the glare from VDT screens causes some users to suffer eyestrain. 
(D) Office workers who experienced frequent headaches were more likely than other workers to overestimate how much time they spent using VDTs.
(E) Office workers who regularly used VDTs experienced the same amount of job-related stress as workers who did not use VDTs.

OA to follow. Please explain the answer choice and reason..

Rock750 · Answer

So, using VDT more frequently causes headaches

This is about causality , if you show that when the effect occurs , the cause doesn't occur then you will weaken the argument for sure.

D weakens the argument showing that even if the effect occurs ( Headaches) the cause does not occur ( Overestimating the amount of time spent using VDT , so it's not necessarly VDT that causes headaches)

A- Wrong, doesn't adress why a population is more concerned about a phenomenon than other is ( too general)
B- Wrong, doesn't attack the cause (VDT) , it talks only about types of migrain experienced by the workers
C- Wrong, clearly Out of Scope
E- Wrong, this option could be correct if it clearly assumes that Stress causes headaches.

joshnsit · Answer

I like your approach. But I will take parts from your answer which I have been trying to grapple.
Causal Argument Conclusion to be focused: VDT more frequently causes headaches.
(D) Office workers who experienced frequent headaches were more likely than other workers to overestimate how much time they spent using VDTs.

Restate of D: 
 More frequent headache bearers overestimate time spent with VDTs. 
Here is excerpt of your first line(also highlighted above):
 Using VDT more frequently causes headaches.

I am not able to compare how D is negatively affecting the causality(In fact, I perceive an inkling of support/strengthen here if I replace "time spent with VDTs" in restate of D with "Using VDT" as in your response. D will then become "More frequent headache bearers if they use VDT  more(as it is not that important) ")

Rock750 · Answer

Okay i get your point

Lets assume that these headache bearers spend in reality 4hours/ day using VDT
But when researchers asked them about the time spent using VDT , headache bearers had overestimated the time say 9hours/day as per option D, leading to a flawed survey. So, we can conclude that even if the effect is there (headache), the cause assumed by researchers is irrelevant.

joshnsit · Answer

Thanks for responding but I am more confused now. :oops:

I considered the choice D as an observed fact targeting other facts in the arguments to weaken the argument. Never looked into choice as a survey. Is this a specific strategy to attack conclusion? :idea:

Let me take the survey approach as well. Wouldn't an irrelevant survey as just indicated above will be similar to the rest of other irrelevant choices A/B/C/E in absence of any hint of causality in choice D? To add to this, in D, we are indirectly crediting the theory that headaches in bearers are somehow correlated with VDTs(though overestimated). Isn't it?

Rock750 · Answer

Ur welcome
The researchers made their conclusion based upon the survey. So, if u show that the answers that they get from the survey are flawed then the conclusion is flawed.
and that what D do ..

Not sure if i get ur second question.

For the third question: yes it is ..

cssk · Answer

Again a typical causal argument that GMAT loves to test. The closer you stick to the causality, the better you can spot the right answer. Now observe the causal relationship in the argument.

Frequent VDT usage causes headaches.

Suppose a relation, A causes B. There are several ways to weaken it.

1) C causes B
2) A does not cause B
3) B causes A (Inverse relation)

Back to our argument. Consider choice D. If people who suffer frequent headaches are likely to overestimate the amount of time they spend using VDTs, then frequent usage of VDTs may not be the reason for headaches among them as they tend to report inaccurate usage. This is the inverse relation that attacks the conclusion by pointing that the survey results cannot be held valid.

Hope I made some sense.

joshnsit · Answer

Thanks guys. OA is D. I also got it in first attempt but it took a while for me to assimilate this choice properly with comments above and below .

Lets assume that these headache bearers spend in reality 4hours/ day using VDT.
But when researchers asked them about the time spent using VDT , headache bearers had overestimated the time say 9hours/day as per option D, leading to a flawed survey. So, we can conclude that even if the effect is there (headache), the cause assumed by researchers is irrelevant.

semwal · Answer

In response to office workers' worries about the health risks associated with using video display terminals (VDTs), researchers asked office workers to estimate both the amount of time they had spent using VDTs and how often they had suffered headaches over the previous year. According to the survey, frequent VDT users suffered from headaches more often than other office workers did, leading researchers to conclude that VDTs cause headaches.
Which one of the following, if true, most undermines the researchers' conclusion?
(A) Few often office workers surveyed participated in regular health programs during the year in question.   We are not concerned with how often one participated in health programmes....  
(B) In their study the researchers failed to ask the workers to distinguish between severe migraine headaches and mild headaches.   Level of headache is not our concern...  
(C) Previous studies have shown that the glare from VDT screens causes some users to suffer eyestrain.  ]We are not bothered about eye strain....  
(D) Office workers who experienced frequent headaches were more likely than other workers to overestimate how much time they spent using VDTs.   ]Means large amount of time spent in front of VDT may not have caused headache.....      CORRECT  
(E) Office workers who regularly used VDTs experienced the same amount of job-related stress as workers who did not use VDTs.  WE are not worried about stress....

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In response to office workers' worries .....

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