V21-32

Question

A five-year clinical trial was conducted to study the effectiveness of hair loss prevention treatments on two different groups of men, all of whom were 25 years old when the trial began. Before the trial began, none of the men had shown signs of hair loss, which is widely believed to be caused primarily by genetic factors. The treatment given to Group A was a pill taken daily for the duration of the trial, and the treatment given to Group B was a topical scalp cream used once daily for the duration of the trial. By the end of the five-year trial, 50% of the members of Group A had experienced some hair loss while only 25% of the members of Group B had experienced some hair loss. Despite these results, the treatment used on Group A was considered significantly more effective in preventing hair loss than the treatment used on Group B.
 
Which of the following, if true, most helps to explain the apparent discrepancy?

A. The members of Group B who experienced some hair loss had, on average, a slightly higher degree of hair loss than the members of Group A who experienced some hair loss.
B. Most members of Group B found using the topical cream to be difficult and inconvenient, while most members of Group A found taking a pill once per day to be easy and convenient.
C. The treatment used on Group B is significantly more expensive than the treatment used on Group A, and, as a result, a relatively small percentage of the target market would be able to afford the treatment used on Group B.
D. Group A consisted of men with a family history of hair loss, while Group B consisted of men with no such family history.
E. Nearly all members of Group B experienced significant side effects such as scalp irritation, unwanted growth of facial hair, and swelling in the hands and feet, while side effects of the treatment used on Group A were rare and minor.

jeffn · Answer

Official Solution:

A five-year clinical trial was conducted to study the effectiveness of hair loss prevention treatments on two different groups of men, all of whom were 25 years old when the trial began. Before the trial began, none of the men had shown signs of hair loss, which is widely believed to be caused primarily by genetic factors. The treatment given to Group A was a pill taken daily for the duration of the trial, and the treatment given to Group B was a topical scalp cream used once daily for the duration of the trial. By the end of the five-year trial, 50% of the members of Group A had experienced some hair loss while only 25% of the members of Group B had experienced some hair loss. Despite these results, the treatment used on Group A was considered significantly more effective in preventing hair loss than the treatment used on Group B.
 
Which of the following, if true, most helps to explain the apparent discrepancy?

A. The members of Group B who experienced some hair loss had, on average, a slightly higher degree of hair loss than the members of Group A who experienced some hair loss.
B. Most members of Group B found using the topical cream to be difficult and inconvenient, while most members of Group A found taking a pill once per day to be easy and convenient.
C. The treatment used on Group B is significantly more expensive than the treatment used on Group A, and, as a result, a relatively small percentage of the target market would be able to afford the treatment used on Group B.
D. Group A consisted of men with a family history of hair loss, while Group B consisted of men with no such family history.
E. Nearly all members of Group B experienced significant side effects such as scalp irritation, unwanted growth of facial hair, and swelling in the hands and feet, while side effects of the treatment used on Group A were rare and minor.

The first step is to identify the discrepancy, using the author's own words as much as possible: "Despite these results (that, by the end of the five-year trial, 50% of the members of Group A had experienced some hair loss while only 25% of the members of Group B had experienced some hair loss), the treatment used on Group A was considered significantly more effective in preventing hair loss than the treatment used on Group B.
 
 What else do we know.. 
 
 All of the men were 25 years old when the trial began 
 
Before the trial began, none of the men had shown signs of hair loss
 
Hair loss is widely believed to be caused primarily by genetic factors
 
The treatment given to Group A was a pill taken daily for the duration of the trial
 
The treatment given to Group B was a topical scalp cream used once daily for the duration of the trial
 
 Based on the information in the passage, there are no major differences between the two groups of men. The form of their treatments was different, but that doesn't tell us anything about the effectiveness of the treatments. So if a larger percentage of Group A experienced some hair loss, why was the treatment used on Group A considered significantly more effective 
 
 We need a statement that helps explain this apparent discrepancy 
 
 (A) The members of Group B who experienced some hair loss had, on average, a slightly higher degree of hair loss than the members of Group A who experienced some hair loss 
 
 Choice A is tempting because it certainly makes the treatment used on Group B seem slightly less effective than we would conclude based solely on the information in the passage. But is this strong enough to explain why the treatment used on Group was considered significantly more effective, even though the percentage of Group A that experienced hair loss was double that of Group B? This doesn't seem like a strong enough answer, but I wouldn't cross it off just yet 
 
 (B) Most members of Group B found using the topical cream to be difficult and inconvenient, while most members of Group A found taking a pill once per day to be easy and convenient 
 
 The treatment used by members of Group A might be significantly more convenient and easier to use than the treatment used by members of Group B, but these characteristics have nothing to do with the effectiveness of the two treatments. We need something that explains why the treatment used on Group A was considered more significantly more effective, not more convenient. Eliminate (B) 
 
 (C) The treatment used on Group B is significantly more expensive than the treatment used on Group A, and, as a result, a relatively small percentage of the target market would be able to afford the treatment used on Group B 
 
 As with the last choice, choice (C) addresses a characteristic--cost--that has nothing to do with the effectiveness of the two treatments. We need a statement that addresses effectiveness, not affordability. Eliminate (C) 
 
 (D) Group A consisted of men with a family history of hair loss, while Group B consisted of men with no such family history 
 
 We are told that "hair loss is widely believed to be caused primarily by genetic factors." Thus, if Group A consists of men with a family history of hair loss, most of those men, without treatment, may have been likely to experience hair loss. Similarly, most of the men in Group B may have been likely to avoid hair loss, even without treatment. In fact, if statement (D) is true, it is possible that the treatment used on Group B had no effect at all. Perhaps, due to genetic factors, only 25% of Group B's members would have experienced hair loss even without treatment 
 
 Remember, we are looking for an answer that most helps to explain the apparent discrepancy. The statement in choice (D) certainly explains why the treatment used on Group B is less effective than it seems based on the facts given in the passage. This statement also explains why the treatment used on Group A was more effective than it seems based on the facts given in the passage. Thus, even though we can't know for sure what percentage of men from each group would have experienced hair loss without treatment, choice (D) helps explain the discrepancy more than choice (A) 
 
 (E) Nearly all members of Group B experienced significant side effects such as scalp irritation, unwanted growth of facial hair, and swelling in the hands and feet, while side effects of the treatment used on Group A were rare and minor 
 
 The amount and degree of the side effects have no impact on the effectiveness of the treatments. One treatment could be considered significantly more effective, even if its side effects are much worse. Thus, choice (E) does not help explain the discrepancy and can be eliminated 
 
 Choice (D) is the only explanation that would explain why the treatment used on Group A might be considered significantly more effective. So choice (D) is the best answer

Answer: D

RenanBragion · Answer

I think this is a  high-quality  question and I agree with explanation.

evelynjw · Answer

I think this questions does not even realistically look at how an experiment should be conducted.

KushagraKirtiman · Answer

I don't agree with the explanation. I dont think the solution is correct. The reason I think so is because if treatment has a numerous side effects then in that case people would always avoid that treatment due to the fear of side effects and their health.

We can counter option C by saying that eventhough group A consisted of people with a history of hair loss but still 50% strike rate cannot be considered as effective mode of treatment compared to group B which has 25% strike rate.

bb · Answer

Thank you for the suggestion and the question.

1. The concept of side effects may be true. It may not be true. The question stem does not state it. It also does not state many other aspects that should be reasonable to assume - e.g. that the study is in the same country, with people of similar body mass, similar stress levels - there is a ton of information we do not have. Side effects is one of them and we don't know if it impacted the study, so we can kind of ignore it. Moreover, since this is the study, and the whole purpose of the study is for people to commit to taking certain treatments. If you committed to participating in the study and you did not actually do it, then you have more issues with the study, so we have to assume that everyone did it and took their stuff on time or applied their cream on time despite huge side effects and problems. because if this is not true, we have lots of other problems and this is all inconclusive.

2. I think you were referring to D rather than C and countering D, the correct answer choice. I believe you also meant Groups A instead of B in your numbers since group A had a 25% hair loss rate and Group B had a 50%. It does not matter by the way - I am not picking on it, just wondering if you may be slightly dyslexic (many people are) and you will have to work that into your answer strategy on the CR. My mind changes answers for some reason and that can be dangerous and wastes time.

Anyway, that's an interesting argument/thought - 50% is 50%. Let me run through the numbers. So let's say Group A had a 50% hair loss rate (family history) and if people were not taking the treatment, let's say in the worst possible case, 100% in Group A would lose their hair so in this (which is a bit extreme for a group that has no history of hair loss). I think in this case the effectiveness is 50% and for group A, let's say it is natural to have 25% lose hair and the treatment was useless. I think the argument becomes treatment A saved hair for 50% of people who otherwise would be losing it while treatment A did not save it for anyone as 25% on average could experience some hair loss... Despite being a bit extreme, I think it works with these numbers, but I am open to suggestions and changing them.

Nestor_Izuit · Answer

I don’t quite agree with the solution. I think this is a high-quality but I find option A as stronger one, option D just makes research irrelevant, if option D is true it is hard to scale results and say wich one is more iffective due to heterogeneity of groups, meanwhule option A offers at least some explentation. I would be glad to have wider explanation. Thank you

bb · Answer

Thank you for the question. This is definitely a tricky one:

At first glance, it does explain something: that maybe Group B’s 25% had worse hair loss, whereas Group A’s 50% only had milder hair loss.

But does that explain why Group A’s treatment is deemed “significantly more effective”? Not really.

Even if Group B’s hair loss is “more severe,” you still have a bigger share of Group A (50%) losing hair. That doesn’t address the contradiction: why would any expert label the Group A treatment “better” when more participants lost their hair overall? If we want to say “Group A’s pill is more effective,” we generally mean fewer people than expected lost hair.

Thus, (A) fails to plug the key hole in the logic: it does not show how 50% vs. 25% is still in favor of the pill.

anushree01 · Answer

I look at it this way to eliminate option A :
Notice the word  slightly  in option A!! 
Question clearly mentions  significant  difference in treatments of A & B, so slightly isn`t very strong strengthner.
Therefore chose option D, which talks about genetical reason.

omnissuscipit · Answer

I don’t quite agree with the solution. In the text, it is said that it is BELIEVED to be caused primarily by genetic factors. Why should we take it as the truth?

bb · Answer

Because this is not the question type where you need to doubt the premise. The goal here is to explain the situation. And in order to explain it, you have to assume it’s accurate.

PS. On the GMAT, specifically in critical reasoning, you’ll notice a pattern of not using the extreme language. And quite often the extreme language is what gives away the incorrect answer. The only exception being there must be true questions but in all the other questions, you’ll notice that the language will be softer, and will use the word such as majority or a significant number or a large portion or most likely and so on.

And there is an understanding in these passages that that’s not used as a place where you need to doubt things but because things are rarely absolute, and to make questions more realistic and void unnecessary arguments, there’s always a small amount of room left for weird edge cases. And if the statement was made an absolute, it would be incorrect. So the whole argument would be incorrect.

For example, most people believe that exercise is good for you. Should we doubt this statement? (if this is a must be true question, then yes, but otherwise no). There’s likely somebody who doesn’t believe this or there’s likely somebody for whom exercise is not beneficial such as someone in the very frail state so stating something such as exercise is good for most people or most people believe exercise is good for them is a way to avoid Being incorrect as the result of an absolute .

omnissuscipit · Answer

Okay, I understood the idea. Thank you very much for the broad explanation!

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