Let me see if I can suggest an easier way to think about this argument, a way that makes getting the answer super easy.
This is a just a causal argument. LSAT has given us HUNDREDS of these over the years. Some of them require great cleverness to get through, but most of them follow a very predictable pattern:
Prem: Correlation between A and B.
Conc: A causes B.
Assumptions/Flaws
- could the causality actually work in reverse? i.e., is it possible that B causes A? (frequently the issue)
- could there be some third factor that really causes B, that's only coincidentally related to A? (frequently the issue)
To strengthen a causal argument, we almost always RULE OUT revere causality or RULE OUT an alternative cause.
EVERY time you see a correlation in the evidence, you should expect that a causal conclusion is around the corner, and immediately start asking yourself, "Could it be reverse causality? Could there be another cause?"
example:
A recent study found that people who drank more than 6 alcoholic beverages a day were more depressed than those who didn't. Thus, drinking excessively causes depression.
Assumptions/Flaws
- Is it possible that being depressed is causing these people to drink excessively? (that's an equally valid way to interpret the correlation given to us in the evidence)
- Is it possible that the people who drink a lot just lost their job or a loved one and THAT'S why they're depressed ?
The key to seeing these arguments coming a mile away is to recognize when you're hearing a CORRELATION. A correlation is just saying that there is a statistical relationship between two things.
People who study for LSAT are more likely to be right handed than left handed. Does that mean that studying for the LSAT is causing them to be right handed? Of course not. That initial correlation is true statistically, but it doesn't prove there's any causal connection between the variables.
Okay, back to #16.
As soon as I read "those who snored frequently were significantly more likely to have serious abnormalities than those who snored rarely", I thought -- correlation! I bet the author is going to conclude that one caused the other.
The conclusion did not disappoint.
So the evidence just says snoring is correlated with throat abnormalities.
Is it possible that throat abnormalities actually cause snoring (rather than the other way around)? Sure.
(E) is the answer because it rules out reverse causality.
----
the first poster wrote the evidence as:
We know:
snoring -> serious abnormalities
snoring-> damage throat of snorers
We shouldn't write a correlation with a conditional arrow. The arrow implies causality. But the whole point of a correlation is that it isn't necessarily causal.
I tend to represent correlations with a couple parallel lines, to say "these two factors are associated more often than not"
Severe depression || Excessive drinking
Studying for LSAT || right-handed
Snoring || serious abnormalities
This doesn't mean left causes right. Maybe right causes left. Maybe both are caused by something else.
===
(A) would probably weaken, if anything. it makes the evidence sound a bit less trustworthy, since self-reported data can often be unreliable.
(B) the throat surgery really has no bearing on the core of this argument. It was only brought up because that's where we got our tissue biopsies. And through studying the tissue biopsies, we saw the correlation between abnormalities and snoring.
(C) this does strengthen the argument, because it makes our data more trustworthy. If we want to prove that snoring caused this damage, we need to control for any other possible variable that otherwise could have caused the damage. This answer controls for some variables, such as age, weight, and state of health.
(like the other poster said, we sometimes have to choose which answer strengthens MOST --- however, in causal arguments, RULING OUT reverse causality and RULING OUT an alternative cause trumps everything else)
(D) again, the throat surgery has no bearing on the evidence for the conclusion. The evidence was a correlation between abnormalities and snoring.
Whew. Long explanation, but extremely important that we know what a correlation is and what the common issues in a causal argument will be.
Let me know if you want clarification on any of what I said.
#officialexplanation
