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#19 - Researcher: In an experiment, 500 families were given

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Lsat180Please
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Hi! I would really appreciate some help with this question because it seemed like there were multiple flaws. Can you please explain why D is the best answer and why A is incorrect? Also, some help with the best way to approach this question. Thanks!!
James Finch
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Hi Lsat180Please,

When we have a flaw question with a causal stimulus, the correct answer is usually one of 4 mistakes the stimulus makes:

1. Fails to consider an alternate cause. The most common type, always think about whether an alternate cause could plausibly exist that causes only the effect, or could cause both the purported cause and the effect.

2. Reverse Causation. There are only so many situations this makes sense, so always test to see if it makes sense to reverse the cause-effect relationship. When it does, that will usually be the correct answer.

3. Assuming causation based on correlation. Is there actually evidence that one thing caused the other, or is it possible that they only tend to correlate, perhaps because they're both caused by some third event?

4. Assuming causation based on temporal sequence. Just because one things happens before another, doesn't mean they're necessarily related--although an effect must always occur after a cause, so this does rule out reverse causation.

Here, we're given both a valid study that utilizes one possible cause (medical self-help books) for the effect of fewer medical visits, and then given a premise about a second cause, family health, that also causes the effect. Where the stimulus goes wrong is assuming that because one thing (family health) can cause the effect, then it must be the only thing that causes it, so the study's cause (medical books) must be causing the known effect (family health), which in turn causes the effect of fewer medical visits.

The problem is that we don't know whether the medical books are leading directly to fewer doctor visits without having any effect on family health; it's plausible that having the medical books in the homes are leading families to go to the doctor less, either because they realize minor illnesses don't require medical attention, or they have a greater belief that they can handle more medical issues themselves, without professional medical attention. And what effect, if any, this has on family health is unknown.

(D) explains this issue with the stimulus in abstract terms (although it could have been explained in a way that is specific to the stimulus) making it the correct answer choice.

Hope this clears things up!
Lsat180Please
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I am still quite confused with D because I thought we only had a correlation between self-help books and doctor visits not necessarily a "cause and effect relationship". I thought by choosing answer D it granted the stimulus a cause and effect relationship, one which we were trying to question as flawed.
prometheus1992
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I believe the flaw in the stimulus's argument can be illustrated with the following diagram:

Has medical textbook → Less visits to doctor
Good health → Less visits to doctor
Has medical textbook → Good health (MISTAKEN INFERENCE)

or more simply:

A → C
B → C
A →B (mistaken inference)

(D) says that the flaw is "two different states of affairs could each causally contribute to the same effect even though neither causally contributes to the other." This would perfectly match the above.

The "different states of affairs" are having a medical textbook and good health and the effect is less visits to the doctor. While it's possible that having a medical textbook (state of affair 1) leads to less visits to the doctor (effect), and good health (state of affair 2) also leads to less visits to the doctor (effect), we can't conclude based on this information that having a medical textbook leads to improved health (improperly assuming causal relationship between two states of affairs).
Dave Killoran
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Yes, I agree. This is what James was describing in his last few paragraphs above, but the idea here is the same. I haven't gotten to the official explanation of this question yet (it's coming!) but when I do it won't look too far off of what you've noted here. Nice work!
Dave Killoran
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Lsat180Please
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Thank you all, this was very helpful!
lsbound22
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Thanks everyone for the responses above. I also choose "a" but would it be accurate to deem as pretty much IRRELEVANT to the conclusion?
Adam Tyson
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I would say so, lsbound22, because that answer tells us nothing about the link between the books and improved health. Answer A might make us question any causal claims about the books and visits to the doctor (because if it were true that the group that wasn't given the book got one anyway, we would have a possible cause without the possible effect). That, however, is something of a side issue, while the main issue is what any of this has to do with improved family health. There could be no connection at all!
Adam M. Tyson
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