We are told that there is a great deal of geographical variation in the frequency of many surgical procedures. Now we need to support the conclusion that much of that variation is due to unnecessary surgical procedure.

So we are given some facts and a conclusion, and we need to select the statement that, if established, would make our argument the strongest. In other words, we are trying to complete the argument with information that would most support the conclusion.

Let's review what we have so far:

• "There is a great deal of geographical variation in the frequency of many surgical procedures."
• What does that variation look like? Well, there is "up to tenfold variation per hundred thousand between different areas in the numbers of hysterectomies, prostatectomies, and tonsillectomies." So the frequency of those procedures varies geographically.
• What causes that variation? Several theories could explain this geographical variation, but we are given one specific theory: "much of the variation is due to unnecessary surgical procedure."

But we don't have any evidence that this theory is correct. We need something that would help support this theory.


(A) is tempting because this could lead to evidence that would support our conclusion. But whether (A) hurts or helps our argument depends on what those local review boards actually find. Perhaps they'll find that, in the areas with high numbers of surgical procedures, many of the procedures were actually unnecessary. That would obviously strengthen our conclusion.

But we can't assume that the boards' results will help our argument. Perhaps the data from the review boards will actually contradict our conclusion. Or perhaps the review boards themselves will have local biases (i.e. different opinions about what constitutes a "necessary" surgery).

Choice (A) MIGHT lead to results that strengthen our conclusion. But, without further information, we can't be sure. We can hang on to this one for now, but (A) is not looking great.


This one's much better. If the variation is actually due to factors that influence the INCIDENCE of diseases that might require surgery, then we would have an explanation that contradicts our conclusion. For example, perhaps people living along the coast are, for some reason, more susceptible to tonsillitis and thus are more likely to require tonsillectomies. This would indeed explain a geographical variation in tonsillectomies and would weaken our conclusion.

If choice (B) is established, then we can eliminate this alternate explanation. That would directly strengthen our argument, so (B) looks good.


Simply knowing that different types of procedures are often performed unnecessarily does not support our conclusion. Do unnecessary surgical procedures explain the geographical variations described in the passage? Choice (C) doesn't support this theory, so eliminate (C).


This statement suggests that it is difficult to distinguish between necessary and unnecessary procedures. This, in turn, suggests that it would be difficult to actually test our theory. If we can't confidently determine that some surgeries were unnecessary, how can we show that unnecessary surgeries explain the geographical variations?

Choice (D) suggests that our theory might be difficult to study, and it certainly does not support our conclusion. Eliminate (D).


Say we have an area that performed ten times as many hysterectomies, prostatectomies, and tonsillectomies as another area. According to our theory, many of the surgeries in the first area were probably unnecessary. This would explain the variation. If we can show that many of the surgeries in the first area were in fact unnecessary, then our theory would look pretty good.

That would NOT necessarily mean that, in general, unnecessary surgical procedures are performed about as frequently as unnecessary hysterectomies, prostatectomies, and tonsillectomies. Maybe, for some reason, unnecessary hysterectomies, prostatectomies, and tonsillectomies are performed much more often than other unnecessary surgeries.

If we can show that hysterectomies, prostatectomies, and tonsillectomies were performed unnecessarily in areas with high frequencies of such operations, then we've demonstrated that our theory is valid. It doesn't matter whether these trends apply to surgical procedures in general. Eliminate (E).

(B) is the best answer.
_________________

The OA is B.

Here is the official explanation:

To establish that much of the varation is due to unnecessary surgical procedures, it is necessary to eliminate that possibility that the geographical varation reflects varation in the incidence of disease treated with these procedures. Choice B, if established, would eliminate this possibility and is thus the best answer.

Review boards (choice A) would provide some control against unnecessary procedures, so choice A would, if anything, tell again the suggested conclusion. Neither choice C nor choice E bears on the conclusion, since neither the conclusion nor the cited geographical variation involves procedures are of the kind choice D describes, the diffculty of determining an individual operation's necessity would merely increase the difficulty of verifying the suggested conclusion.

No, this is not an assumption question.

The question asks us to identify the option which will best allow us to determine whether much of the variation in surgical procedures across geographies is due to unnecessary surgical procedures.

A: Incorrect. Even if a local board reviews for the necessity of surgical procedures, we have nothing here to tell us whether they end up recommending unnecessary surgical procedures
B: CORRECT. If the variation is unrelated to factors related to the incidence of diseases, then it must be a result of incorrect recommendations being made
C: Incorrect. Even if a large number of surgical procedures are incorrectly recommended, we do not have enough information to conclude that the variation is a result of these
D: Incorrect. If it is difficult to determine whether the procedures were necessary, it will be more, and not less difficult to determine the need for them
E: Incorrect. Similar to C.

(B) is therefore correct.
_________________

The below explanation is from David (Veritas Prep) -

This is a special type of the strengthen question where the conclusion is in the question stem. Please be on the lookout for this as it occurs fairly regularly.

The conclusion is "much of the variation is due to unnecessary surgical procedures" This indicates a cause and effect relationship. We are, in effect, saying that the reason that there is a geographical variation in the listed procedures is because in the areas where more procedures are performed many of those procedures are not necessary.

Now there could be other reasons for a variation in the number of surgeries. For example, the new natural gas wells that are being drilled in people's back yards have been proven to contaminate the water supply and so it would be very reasonable to see additional cases of cancer and therefore additional procedures near these poisonous wells. So that would be another cause not unnecessary procedures, but variations in the toxicity of various places around the U.S. (or the world depending on how you read the question).

In order to strengthen a question that involves cause and effect, you will want to consider the possibility of blocking an alternate cause. In this case we are saying the cause is the "unnecessary procedures" so we want to block the things that would make these procedures necessary - like variations in the age of the population, the health of the people, the quality of the water, even the ability of the people to pay for the procedures.

Answer Choice B does this. It says, "The variation is unrelated to factors (other than the surgical procedures themselves) that influence the incidence of diseases for which surgery might be considered." So this blocks the idea that the cause of varying rates of procedures would be any of the factors (age, health, toxins) etc. mentioned above. So we strengthen one cause by blocking another.

GMATNinja ,RonPurewal , sayantanc2k ,mikemcgarry ,daagh ,egmat ,EMPOWERgmatRichC ,
ChiranjeevSingh , AjiteshArun
other experts -- can you please help with a detailed explaination to eliminate other options!!
_________________

There is a great deal of geographical variation in the frequency of many surgical procedures—up to tenfold variation per hundred thousand between different areas in the numbers of hysterectomies, prostatectomies, and tonsillectomies.

To support a conclusion that much of the variation is due to unnecessary surgical procedure, it would be most important to establish which of the following?

(A) A local board of review to each hospital examines the records of every operation to determine whether the surgical procedure was necessary. --It weakens the argument

(B) The variation is unrelated to factors (other than the surgical procedures themselves) that influence the incidence of diseases for which surgery might be considered. --Correct. It removes the possibility that any other factor might impact the procedure

(C) There are several categories of surgical procedure (other than hysterectomies, prostatectomies, and tonsillectomies) that are often performed unnecessarily. --Out of scope

(D) For certain surgical procedures, it is difficult to determine after the operation whether the procedures were necessary or whether alternative treatment would have succeeded. --This weakens the argument

(E) With respect to how often they are performed unnecessarily, hysterectomies, prostatectomies, and tonsillectomies are representative of surgical procedures in general. --Out of scope

Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.