There is a great deal of geographical variation in the frequency of ma

Question

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.

(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.

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

(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.

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

MIT Technology Review, April 1987

There is a great deal of geographic variation in the use of many surgical procedures — up to 10-fold differences in hysterectomies, prostatectomies, and tonsillectomies among different areas.  The variations seem unrelated to disease incidence and death rates, and have no discernible effect on the general health of the population.  In part, the unnecessary use of medical technologies and procedures stems from the poor quality of much clinical

GMATNinja · Accepted Answer

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.

ywilfred · Answer

1) There is a great deal of geographical variation in the frequency of many surgical procedures

2) Up to tenfold variation per hundred thousand people between different areas in the numbers of hysterectomies, prostatectomies, and tonsillectomies. 

Conclusion: Variation is due to unnecessary surgical procedures

A: A local board of review at each hospital examines the records of every operation to detemine whether the surgical procedure was neccesary. 
- Does not tells us that redundant surgical procedures cause variations

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. 
- Explains that variation is due to the surgical procedures alone and nothing else

C: There are several categories of surgical procedure(other than hysterectomies, prostatectomies, and tonsillectomies) that are often performed unneccesarily. 
- Does not explain the conclusion

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. 
- Not useful

E: With respect to how often they are performed unneccesarily, hysterectomies, prostatectomies, and tonsillectomies are representative of surgical procedures in general.
- Not useful

B is best.

jinino · 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.

walker · Answer

For me, B is clear and typical for GMAT:

--?->  
We need: there is no other cause (but surgical procedures) that results in

At the same time, C is also a typical trap: it says something about other surgical procedures (out of scope), but we consider here the variation in the numbers of hysterectomies, prostatectomies, and tonsillectomies.

GyanOne · Answer

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.

LogicGuru1 · Answer

Like Word problems in algebra, it is very important to assimilate the questions in CR and then simplify them in common terms

THE QUESTION IS 
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.
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.
C)There are several categories of surgical procedure (other than hysterectomies, prostatectomies, and tonsillectomies) that are often performed unnecessarily.
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.
E)With respect to how often they are performed unnecessarily, hysterectomies, prostatectomies, and tonsillectomies are representative of surgical procedures in general.

The question is making us to pick the assumption, which is noting but an understated premise. SO we have to pick an answer that is the assumption made to derive the conclusion. This argument can be simplified and broken into premises and conclusion as follows :-

Premise 1 ) There is a huge variation in number and type of surgeries in a country. Location A has 300 eye surgeries, Location B has 200 heart surgeries and Location C has 400 kidney surgeries. 
Premise 2) ----- NOT GIVEN------
NO OTHER PREMISE IS GIVEN. WE ARE DIRECTLY GIVEN A CONCLUSION AND ASKED TO PICKED THE MISSING PREMISE 2

CONSLUSION ) These surgeries were unnecessary.

If you look at Premise 1 only, you might conclude that many people in location A are suffering from eye disease. Population of Location B suffers from a heart disease, and Location C has some disease that is affecting the kidneys of many people. That is the reason there is no much variation in each location and its disease type. These diseases must be dangerous if not treated urgently.

But then comes the conclusion that say :- THE SURGERIES WERE UNNECESSARY.
Now, If we add a premise such as :- This variation is not caused due to the difference in number of people suffering from eye, heart and kidney disease.

How does our argument now looks like ?? ==>
Premise 1 ) There is a huge variation in number and type of surgeries in a different parts of the country. 
Premise 2) This  variation in surgeries is NOT because  different people suffer from different disease in different location.
Conclusion) If these variations are not because people were suffering==> then these surgeries were unnecessary.

Skywalker18 · Answer

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!!

AjiteshArun · Answer

The stimulus says  there is a great deal of geographical variation in the frequency of  many  surgical procedures . The  many  is important here. The stimulus is not saying that there is variation in the frequency of every possible procedure—just in "many". Then the stimulus tells us which procedures form the "many" (hysterectomies, prostatectomies, and tonsillectomies). If you're not sure about this, read the stimulus as "there is a lot of variation in the frequency of many surgical procedures—up to tenfold variation in A, B, and C procedures". The part after the dash limits the scope of the question. This is different from trying to change the "degree" with something like "there is a lot of variation in the frequency of many surgical procedures— and  up to tenfold variation in A, B, and C procedures".

The conclusion is that this variation can be explained by unnecessary surgical procedures. We need to strengthen this, so  the correct option will help us believe that unnecessary hysterectomies, prostatectomies, and tonsillectomies are being performed in some areas  (more frequently than in others).

This option says that there is (already) a local board of review at every single hospital. If such a board reviews surgical procedures to check whether they were necessary or not, we are LESS likely to believe that the variation is due to unnecessary surgical procedures.

Keep in mind that this option is not presenting us a recommendation. It tells us that such boards are  already  in place. Also,  don't add any extra information  (like "the boards are not functioning well").

This is good. The conclusion is that the variation is due to X. This option strengthens that conclusion by saying that the variation is unrelated to factors other than X (leaving only X to explain the variation).

This option (a) discusses procedures other than the ones the question is concerned with and (b) gives us no information about the link to  geographical variation . If it had said that the same geographical variation is observed in other categories, we would have had  some  reason to think that the variation observed in the frequency of hysterectomies, prostatectomies, and tonsillectomies is due to unnecessary surgical procedures. But this option doesn't do that. It just says that there are other procedures that are often performed unnecessarily.

If this is true,  all geographical regions should find the process equally difficult . There's nothing here to suggest that there is any geographical variation in the frequency of unnecessary surgical procedures. Also, this option doesn't really specify whether "certain" includes hysterectomies, prostatectomies, and tonsillectomies.

Whether the three are representative or not is irrelevant. We first need to establish that the variation in the frequency of the three procedures is in fact due to unnecessary surgical procedures.

unraveled · Answer

I faltered in this one - may be because of the overall structure of passage - and fell for trap answer C. Here's my post attempt analysis.

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. -   Here's a fact laid down in the passage by the author that there is geographical variation in the frequency of many surgical procedures(SP). 'up to' suggests the maximum variation possible between different areas for H, P and T. It can be considered as example given in support of the fact that there is vast amount of variation.

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? -   'To support' suggests that we need to strengthen the argument/conclusion. Conclusion is that much of the variation is due to unnecessary surgical procedure(USP). So, in order to do so, what must be done?

Till this point, we understood that we need to EITHER disapprove/weaken any fact that says that the variation is because of surgical procedures OR support one which suggests that variation is due to some other unsought USP. However, latter is far better for our case.

(A) A local board of review to each hospital examines the records of every operation to determine whether the surgical procedure was necessary. -  This goes in either of the directions as we are more interested in the result the review would get us. Was it necessary or was it not?

(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. -  The phrasing is little confusing. All it says that unrelated factors to SPs caused the variation as they(unrelated factors) let to surgeries. Some local factors related to geography led to some disease and thus surgeries.

(C) There are several categories of surgical procedure (other than hysterectomies, prostatectomies, and tonsillectomies) that are often performed unnecessarily. -  The word 'several' if replaced by 'some' then probably it becomes clear that this is not the right answer. Also, SPs other than H, P and T, if performed unnecessarily, would suggests that variation was indeed because of SPs and not USPs. H, P and T variation is given as an example - an extreme one - and suggests that there are other SPs which might be necessary. What if we have another extreme case where the variation is minimal geographically and most of the cases have such minimal variation? OR What if H, P and T is an exception among the cases? The passage actually doesn't touches upon this aspect. The point is this is an open choice like A, which leads us to nowhere.

(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. -  Again, generically speaking, we are not concerned of certain SPs. Are those 'certain SPs' number most OR least OR exception. Basically this is irrelevant.

(E) With respect to how often they are performed unnecessarily, hysterectomies, prostatectomies, and tonsillectomies are representative of surgical procedures in general. -  The word 'how' jumps in and we are not concerned how H, P and T are performed unnecessarily. Again Irrelevant.

I don't know if this analysis is good or bad but this is how i understood it.

Answer B.

jabhatta2 · Answer

Hi  AndrewN  - i could not understand what (E) is saying - is it saying ?

--------------

Unnecessary  hysterectomies |  Unnecessary  prostatectomies |  Unnecessary  tonsillectomies

are taking place at the same rate as

Unnecessary  other surgical procedures (For ex - Appendectomies, Carotid endarterectomies...) ?

AndrewN · Answer

Yes,  jabhatta2 , answer choice (E) is saying that the three types of procedure in question are not performed any more frequently than are other procedures when any of these procedures are unnecessary.

Well done transcribing a pretty difficult answer choice.

- Andrew

Elite097 · Answer

ThatDudeKnows   avigutman  I am not clear on what choice D and E mean and why they are incorrect and how they relate to the passage

avigutman · Answer

Passage describes a phenomenon that requires some explanation: surgeries are performed at different rates in different geographies.
For example, imagine that you find out that only 5 hysterectomies per 100,000 people are performed in Japan, whereas 50 hysterectomies per 100,000 are performed in India. 
One possible explanation for this phenomenon is that the excess hysterectomies in India (45 more than Japan, per 100,000) are unnecessary. Our task is to find an answer choice that supports this particular explanation.
(D) suggests that we might not be able to tell whether the procedure was necessary, even after the fact.
(E) closes a gap between the premise and the conclusion: the premise was specifically about hysterectomies, prostatectomies, and tonsillectomies, whereas the conclusion was about surgical procedures in general.
Please let me know whether that helps,  Elite097 .

Jarvis07 · Answer

To support a conclusion that much of the variation in the frequency of surgical procedures is due to unnecessary surgeries, it would be most important to establish option 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.

If there are other factors (such as differences in the incidence of diseases or patient preferences) that explain the variation in surgical procedures, then it would be difficult to conclude that the variation is due to unnecessary surgeries. Establishing that the variation is not explained by these other factors would support the argument that the variation is due to differences in physician behavior or practice patterns, which could include performing unnecessary surgeries.

Options A, C, D, and E are not directly relevant to the argument that much of the variation in surgical procedures is due to unnecessary surgeries. Option A addresses the process for reviewing surgeries after they have been performed, but it does not speak to the underlying causes of the variation in the first place. Options C and E are concerned with other categories of surgical procedures, but they do not speak to the causes of the variation in the frequency of the specific procedures mentioned in the prompt. Option D is concerned with the difficulty of evaluating the necessity of certain surgeries after they have been performed, but it does not speak to the underlying causes of the variation in the frequency of surgeries.

ABCFAJ · Answer

Request you to change the question tag to Assumption. This is not an evaluate question

stackskillz · Answer

Conclusion : Unneccesary surgeries are the cause for the variation cited in the passage.
 Type : Strengthen/Support

(A)  A local board of review to each hospital examines the records of every operation to determine whether the surgical procedure was necessary  - This tells us that a local board does review whether each surgery recommended is necessary or not. However, this does not tell us regarding their conclusion, i.e., did the board come to the conclusion that the surgeries were necessary and in what percentage of cases? This option has no impact.  Drop

(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.  Okay. Sounds complex, but let's break it down. Variation is not related to the incidence of the diseases for which surgery is required, i.e., Incidence/frequency of diseases is not the cause for surgery. This option eliminates an alternate cause for variation cited, hence it's a strengthener.  Keep

(C)  There are several categories of surgical procedure (other than hysterectomies, prostatectomies, and tonsillectomies) that are often performed unnecessarily.  Sounds like a conclusion in and of itself and doesn't provide the link for cause-effect chain.  Drop

(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.  - Whether it can be determined whether the procedures were necessary or not only tells us about the testing feasiblity, but not the cause-effect link between unnecessary surgeries and the geographic variation.  Drop

(E)  With respect to how often they are performed unnecessarily, hysterectomies, prostatectomies, and tonsillectomies are representative of surgical procedures in general.  Does this mean that most if not all surgeries are performed unecessarily? That maybe so, but why? Well this option doesn't answer that.  Drop

Contropositive · Answer

Hi  AjiteshArun  Thanks for the awesome, crisp explanation. I was just going through it to make sure that i have eliminated wrong options for right reasons.
I eliminated (A) for different reason, but i am not sure whether the logic is right.

Question says that i should support the conclusion that ''unnecessary surgical procedure'' is causing ''geographical variation in the frequency of many surgical procedures''
 
I went onto extreme and thought: Okay local board have found that every operation was unneccesary. So what? It may just explain the correlation between ''unneccesary'' and ''frequency variation''. So unless no option is better, this can be the answer.

On the other hand, (B) removes a potential cause. Hence it makes more probable that ''unnecceasry operation'' was the cause.

AjiteshArun · Answer

Hi Contropositive,

Thank you for the kind words. You're absolutely right about option B. As for option A, exploring extremes can be useful, but we shouldn't go overboard with edge cases.

Instead, let's take a look at the question stem: "To  support  a  conclusion  that much of the variation is due to unnecessary surgical procedures...". This is a basically a strengthen question, so if we put the correct option into the argument, we should get a stronger argument. However, if we go with option A, this is the argument we get:

Premise1 (stimulus) : There is a lot of geographical variation in the frequency of many surgical procedures.
 Premise2 (option A) : A local board of review at each hospital examines the records of every operation to determine whether the surgical procedure was necessary.
 Conclusion (stem) : Therefore, much of the variation is due to unnecessary surgical procedures.

If we have an additional check/verification/review of some kind, of every single operation performed, does that help or hurt the conclusion? You could also approach this another way. If this were a weaken question, would you consider option A a possible answer?

KarishmaB · Answer

Premises: 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. Conclusion: Much of the variation is due to unnecessary surgical procedures. We need to strengthen this conclusion. It involves causation. We are given that 'Unnecessary surgical procedures' is the cause of 'great deal of geographical variation in the frequency of many surgical procedures' Say in country X, 100 women out of every 100,000 get a hysterectomy. But in country Y, 1000 women out of every 100,000 get a hysterectomy. The author says that the wide variation in the two countries is because of 'unnecessary procedures in Y'. That doctors do unnecessary procedures in country Y (perhaps to make money or whatever) We need to strengthen that this indeed is the cause of variation. How do we strengthen 'A (unnecessary surgeries) is the cause of B (variation in number of surgeries)'? By saying that C, another possible cause is not present. That is what option (B) does: (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. This says that the variation in the number in X and Y is unrelated to factors that influence the incidence of diseases for which these surgeries are needed. Say, genetic issues cause diseases that lead to hysterectomy. This option tells us that Y does not have people more inclined to these genetic issues. It says that the variation (only 100 in X and 1000 in Y) is not related to factors (genetic inclination) that influence the incidence of diseases for which surgery is done. So he saying that we DO NOT see more genetic inclination to these diseases in women in Y. 'Variation in factors that influence the incidence of disease' could have been an alternative cause of variation in number of surgeries. So if women in Y were genetically more prone to uterine diseases, then it could explain the high number of hysterectomies. This option tells us that this alternative cause (C) is not responsible for B (variation in number of surgeries). Hence it supports that A is the cause of B. (A) A local board of review to each hospital examines the records of every operation to determine whether the surgical procedure was necessary. Does it support that unnecessary surgeries are conducted in Y? No! If anything, it says that some strict measures are taken to keep a check on whether surgeries are necessary or not (whether the board is effective in keeping a check on number of unnecessary surgeries we don't know so I wouldn't call this a weakener) but it certainly isn't a strengthener for the given cause. (C) There are several categories of surgical procedure (other than hysterectomies, prostatectomies, and tonsillectomies) that are often performed unnecessarily. It doesn't talk about the variation in the number of procedures performed. Say this option tells us that bariatric surgeries are often performed unnecessarily. But it doesn't say that there is a variation in the number of bariatric surgeries in X and Y. Hence these surgeries are out of scope for us. We are talking about those in which there is wide geo variation. (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. 'Certain surgical procedures' are irrelevant to us. If it is difficult to determine whether the procedures were necessary, then it would be so for doctors in both X and Y. We need to get data on those procedures for which there is a wide variation in the number of surgeries in X and Y. (E) With respect to how often they are performed unnecessarily, hysterectomies, prostatectomies, and tonsillectomies are representative of surgical procedures in general. This tells us that if 50% of the hysterectomies (and other 2) are unnecessary, then 50% of other procedures are also unnecessary. It doesn't say anything about the geo variation. Answer (B) Check this video: https://youtu.be/mB8bm_a4GNk

There is a great deal of geographical variation in the frequency of ma

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There is a great deal of geographical variation in the frequency of ma

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