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#18 - An article claims that many medical patients have

Nikki Siclunov
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The following analysis of Question #18 is in response to a question posted to our Blog:

Nikki - in real time, I would never be able to get the two ( #18 and 24) LR q's that you referenced above. It took me close to an hour just to unpack both questions. I had never seen anything like either before in any previous exam. Could you simplify or break down the structure for either of them so that the next time we are unfortunate enough to come across them, we can more readily recognize them? Thanks for the recap and for your time.

http://blog.powerscore.com/lsat/october-2015-lsat-preptest-76-logical-reasoning-overview


Hi Mariel,

Thanks for the question! Let's take a look at Question #18 first.

The stimulus contains an argument, and – as always – simplification is key. The author does not buy the rumor that patients can predict sudden changes in their medical status. Why is she so skeptical? Because she considers the rumor to be analogous to another, already disproven rumor, namely, that there are more babies born during full moons than at other times. The author points out that there is no correlation between busy maternity wards and full moons; the reason why we think there is one is that the busy nights with full moons are more memorable that the busy nights without them! In other words, a memorable coincidence creates an illusion that something special is actually happening.

Is the same illusory perception affecting our belief that patients can predict sudden changes in their medical status? The author assumes as much. The analogy can only pass muster if we assume that a patient’s correctly predicting a change in his medical status (a memorable coincidence) is more likely to be remembered by the medical staff than if the prediction wasn't correct, and no change occurred. Just like the medical staff is more likely to remember the busy nights with full moons, they should also be more likely to remember when the patient correctly predicts a change in his medical status. For the two rumors to be analogous, we need to assume that in both of them a memorable coincidence creates an illusion that is ultimately untrue.

This prephrase agrees with answer choice (B), which states that a patient’s prediction is less likely to be remembered if no change occurs (i.e. the prediction is inaccurate). The corollary to this statement is that a patient’s prediction is more likely to be remembered if it actually proves true. This is precisely what I was looking for. If answer choice (B) weren’t true, and the likelihood of remembering a patient’s prediction is not affected by whether or not the change actually occurs, then the two rumors would be materially different, and what makes one of them illusory may not apply to the other. Since the logical opposite of answer choice (B) weakens the conclusion, this answer states a claim upon which the conclusion depends.

I hope that makes sense. It’s a tough question for sure, so I’m glad you asked for an explanation.
Nikki Siclunov
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cecilia
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Thank you Nikki!! Awesome explanation.

Lingering question on (A), which I fell for. Had it not used the word "soon", could it have been correct?
Ladan Soleimani
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Hi Cecilia,

Answer choice (A) can be tempting because the stimulus tells us that the case with babies being born in disproportionally high numbers on the full moon has already been disproven. It seems to make sense that if it is an analogous case, then patients being able to predict their medical status would also be disproven. However, it misses the main point of the analogous case, which is what Nikki has explained above. "The analogy can only pass muster if we assume that a patient’s correctly predicting a change in his medical status (a memorable coincidence) is more likely to be remembered by the medical staff than if the prediction wasn't correct, and no change occurred."

Remember, for an assumption question you are looking for what is required for the conclusion to be true. For this argument it is necessary that correctly predicted changes in medical status by patients are remembered more often, otherwise the analogy doesn't work and the argument falls apart. It is not necessary for this to be disproven 'soon' or ever. The Assumption Negation Technique might make this clearer. If you negate answer choice (A), to get that the article will not be empirically disproven, then it still doesn't weaken the argument. Just because the article is not disproved does not mean that the article is true and the argument still works. Would answer choice (A) be helpful to the author's argument? Yes, but it isn't required so it cannot be the assumption.

I hope that makes sense!
Ladan
cecilia
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Thanks Ladan for the reinforcement! It helped a lot.
emilysnoddon
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Why is D not an assumption of the argument?
Clay Cooper
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Hi emily,

Thanks for your question.

Answer choice D is incorrect because the claim in it does not have to be true in order for the conclusion to be true. The conclusion is that the anecdotal evidence regarding predicting sudden changes in medical status should not be trusted.

Answer choice D states that babies are less likely to be born on a night with a full moon than on a night without a full moon. The author of this argument doesn't depend on this being true. In fact, I doubt he would agree with it; by bringing up the disproven reports of higher numbers of births on nights with full moons, he is just illustrating the same phenomenon he thinks is at work here: systematic biases in human memory.

Furthermore, negating answer choice D would yield a claim that it is not the case that babies are less likely to be born on a night with a full moon than on a night with a less than full moon. This statement, if true, does not attack our conclusion; thus, the negation technique warns against choosing D.