Q2 - Psychologist: A study of 436

[ManhattanPrepLSAT1]

Question Type
Flaw

Stimulus
The argument concludes that it is likely that napping causes insomnia. Why? Because a study has indicated a correlation between taking short naps and insomnia. Moreover, people who work on commercial fishing vessels frequently take naps and often suffer from insomnia.

Answer Prephrase
The argument mistakes a correlation for a causal relationship.

Correct Answer
(D) is correct. The argument fails to consider that the correlation between napping and insomnia may have the causal relationship the wrong way.

Incorrect Answers
(A) is out of scope. The argument doesn't compare university students to the general public, but rather university students who frequently took naps with those who did not.

(B) is too strong. The argument posits one cause of insomnia, but does not suggest it is the only cause.

(C) is out of scope. The term napping need not be scientifically defined.

(E) is out of scope. The argument correlates commercial fisherman who have irregular sleep patterns with insomnia. But whether there is such a thing as a regular sleep pattern for commercial fisherman is out of scope.

#officialexplanation

[alex.chasan]

I had trouble choosing between (B) an (D) on this one, but it still seems like the argument is flawed on both these grounds so I'm having trouble seeing how (B) is necessarily wrong.

What we know is:
-A study of University students found those who nap suffer from insomnia more frequently
-Fisherman who nap also suffer from insomnia
So the Psychologist concludes that:
-Napping tends to cause insomnia.

My take on this is that it is a *very* weak argument because it makes almost every error of causality there is....
1. It generalizes from unrepresentative samples which leaves it particularly vulnerable to the possibility that there is a 3rd, "lurking", variable causing BOTH the insomnia AND the napping
2. It assumes causality on the basis of some correlation
3. It clearly overlooks the possibility that the direction of the causality, if there is causality, could be reversed.

The reason I have a hard time accepting (D) as the right answer, is that in order to do so, you have to presume that there is, in fact, a causal relationship here...which is far from clear on the basis of the weak evidence the author supplies.

(B) is not great either, but it seemed more parsimonious because you don't have to take the extra step of accepting causality in the first place.

I must be missing something here...does anyone have another take on this?

[cyruswhittaker]

The argument's conclusion is that napping tends to cause insomnia.

B says that the argument presumes ALL instances of insomnia have the same cause.

But the argument does not do this. Afterall, it would be wholly consistent with the argument's conclusion to say: "Drinking lots of coffee right before bed also causes insomnia."

All the argument is saying is that napping is a cause, not that napping is the only cause of insomnia.

Choice D is correct because by merely showing that the argument fails to "consider" this effect of reverse causation, it has effectively attacked the argument, as the conclusion is specifically causal in nature. However, it is not necessary to presume this is true, as its validity is irrelevant, as it is simply a means by which to attack an underlying assumption.

In fact, this is inherent in the way the criticism is phrased: "fails to consider the possibility..."

[missbenyamin]

Breakdown of Stimulus:

P1: Those who took short naps... more insomnia.

P2: People who work on commercial fishing vessels...irregular sleep patterns...also suffer from insomnia.

C: Napping -->(causes) Insomnia.

Analysis: This stimulus represents most common reasoning flaw - that of causation (claim of one element having impact on another.)

The author fails to consider:
1. Insomnia may be leading to napping (B --> A, vs. original conclusion that claims A --> B)
2. 3rd variable is leading to both
3. Simply correlation; there is no causation involved

Qstem: Identify a Flaw
Task: Identify Flaw in relationship between P + C - NOT evaluate validity of premise, NOT evaluate validity of conclusion in and of itself)

Approach: Eliminate answer choices even if you have strong indication of correct answer

Challenges for this Qtype: (1) abstract language (2) answer choice presented from different perspective

Breakdown of ACs:
(A) - incorrect b/c has no effect on argument core
(B) - incorrect b/c does not accurately represent stimulus (the original conslusion states that "napping tends to cause insomnia... no mention of it being the only cause!)
(C) - incorrect b/c it is irrelevant to argument; we do not need a definition of napping in order to see see the link (or flaw in the link) between premise and conclusion
(D) - correct; accurately presents one of three possible alternative explanations presented above in our analysis - namely, that B (insomnia) may be causing A (napping,) as opposed to the other way around, which is what is suggested in the original conclusion
(E) - incorrect b/c does not directly impact gap between premise and conclusion