Complete Question Explanation
Assumption. The correct answer choice is (B)
The scientists conclude that autistic children can benefit at an earlier age from the treatments available for autism, because the new test correctly diagnosed 100% of them when they were 18-months old, even though it gave 2 false positive diagnoses. Notice that the information about the false positives is mostly meant as a distraction, since diagnosing as autistic children who do not suffer from autism is irrelevant to a conclusion that autistic children can benefit from the treatments available. Of course, the more false positives there are, the less reliable the test will be — raising questions as to whether the test should ever be used as a reasonable basis for treatment decisions in the first place.
When analyzing the relationship between the premises and the conclusion, ask yourself if there is anything missing or wrong with this argument. Just because an autistic child is diagnosed at 18 months as such does not necessarily mean that he or she can benefit from the treatments already available. What if these treatments require advanced verbal or linguistic faculties to be effective? Indeed, the conclusion only follows if the treatments already available can work on 18-month old children, and only if the diagnostic test can provide a reasonable basis for the decision to treat. Answer choice (B) is therefore correct.
Answer choice (A): The first sentence in the stimulus explicitly states that the new test can, for the first time, accurately diagnose autism in children as young as 18 months old. Answer choice (A) can be inferred from this information, but is not required by it. This is a good example of the difference between Assumption and Must Be True questions: an assumption is a statement that precedes (or is required by) the conclusion; an inference is merely something that follows from it. This answer choice is incorrect.
Answer choice (B): This is the correct answer choice. The conclusion necessitates the possibility that such test can provide a reasonable basis for treatment decisions. Imagine if a diagnostic test that sometimes falsely gives a positive diagnosis could not provide a reasonable basis for treatment decisions? This would certainly weaken the scientists' argument. Therefore, answer choice (B) is correct.
Answer choice (C): This is one of the most attractive decoy answers in this question. At first glance, it appears that the ability of the new test to evaluate all children is required for the conclusion to be true. However, this answer choice goes too far. It is not necessary that the test can evaluate all children: do we need the ability to evaluate a 1-month old baby? A 1-day old baby? Certainly not. The assumption is that the new test can evaluate children as young as 18 months old, not any child in general. Always ensure that your assumption answer is minimalist and limited in scope to the conclusion at hand. An assumption answer that goes too far may be useful in strengthening the argument, but will not be necessarily required by it.
Answer choice (D): This is another attractive decoy answer, as it seemingly serves to dissuade the fears that the falsely diagnosed children will suffer no adverse side effects from being treated for autism. As discussed earlier, however, the well-being of children who do not suffer from autism is tangential to the focus of this argument and is not required by its conclusion, which is about autistic children alone. While answer choice (D) strengthens the argument by suggesting that the children incorrectly identified as autistic will not suffer from being treated for autism, the conclusion does not rely upon it. This answer choice is incorrect.
Answer choice (E): Whether we knew that autism could affect children so young is irrelevant to the argument. This answer choice is incorrect.
#17 - Reporter: A team of scientists has recently devised a
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Hello. Can someone help me understand the language of answer B. The answer states that, "a diagnostic test that sometimes falsely gives a positive diagnosis can still provide a reasonable basis for treatment decisions." I do not understand what this answer means (the bolded).
Moreover, the answer key in the student center explains that the stimulus in this question, "Just because an autistic child is diagnosed at 18 months as such does not necessarily mean that he or she can benefit from the treatments already available." How does this connect with the answer B?
Since this is an assumption question, you are looking for what must be true for the conclusion to be true. The stimulus presents a new diagnostic test for autism that was able to correctly identify all the children with autism, but also misdiagnosed 2 children who did not have autism. The conclusion is that children can benefit from treatment earlier because of this test. What is necessary here is answer choice (B): a diagnostic test, like the one in the stimulus, can provide a reasonable basis for treatment decisions, which is what the conclusion is claiming, even if it sometimes gives a false positive diagnosis, like this test did with the two children who do not have autism. If we use the negation technique and change the answer choice to: a test that can give a false positive result CANNOT provide a basis for treatment, then the argument in the stimulus does not work.
The explanation you mention "Just because an autistic child is diagnosed at 18 months as such does not necessarily mean that he or she can benefit from the treatments already available" is not directly tied to the correct answer. It is however, an problem with the argument. The treatment options that are currently available may not be suitable for an 18 month old child. So even though children can be diagnosed earlier, it does not necessarily follow that they will benefit from current treatments.
Hope that helps!
I understand why B is the correct answer, but I am still having trouble with the reason A is incorrect. The conclusion states autistic children can benefit much earlier than they can from other available treatments.
I negated answer choice A to state, " Other tests for diagnosing autism at such an early age did exist prior to the new test." Hence, I thought this was sufficient in weakening the conclusion. Could you please explain my flaw in reasoning? Thank you!
Hey there, ginapark96, thanks for asking! The issue with answer A is one of accuracy. The stimulus tells us that the new test is the first one that accurately diagnoses autism at that young age. That doesn't mean it was the first test intended to do that, but just the first one that actually works well! Answer A doesn't have to be true because there could have previously been some other test that was intended to do the job, but which was not accurate.
Every word matters on the LSAT, so read carefully! "Accurate" vs "intended" is a crucial difference, and you have to pay attention to those differences in every stimulus, stem, and answer choice in order to do well on this harsh test.
Keep at it, and keep coming back for help as needed!
Adam M. Tyson
PowerScore LSAT, GRE, ACT and SAT Instructor
Follow me on Twitter at https://twitter.com/LSATadam
I have a question regarding answer choice A.
The stimulus states that a team has recently devised a new test... and concludes with "Autistic children can now therefore benefit earlier in life than before from the treatments already available."
It seems to me that the author is assuming that this team was indeed the first to devise such a test to conclude that "children can now therefore benefit earlier." It could be the case that it is new to the team but that some test adept at diagnosing children as young as 18 months was already in existence.
Very good analysis!
The problem is that there is an important difference in the test described in answer choice (A). Answer choice (A) does not stipulate whether any earlier test was "accurate." Further, if there had been an accurate earlier test, this statement would contradict the premise in the stimulus which states:
The author does not assume there was no such accurate test. He or she states this information as a fact in the beginning of the stimulus.
The author need not assume that there had been no other test before this new one, only that previous tests had not been accurate. As noted above however, even this fact is not an assumption for the purposes of this argument, since we know from a premise that no previous test had accurately diagnosed children as young as 18 months.
The point about whether a "team" developed the test or not does not change the information about the existence or nonexistence of an accurate test. The team developed a new test, and this test was the first test to be accurate at 18 months according to the premise. According to the facts in the stimulus, there had been no such previous accurate test, whether or not this (or any other) team developed it.
I hope this helps!
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