Q17 - After monitoring blood levels of lycopene

[ohthatpatrick]

Question Type:
Weaken

Stimulus Breakdown:
Conclusion: Lycopene reduces the risk of stroke.
Evidence: In this study, people with low lyco were twice as likely to have a stroke.

Answer Anticipation:
Let's dust off the ol' 2-pronged causal prephrase.
CURIOUS FACT: Why did the people with low lyco have more strokes than the people with higher lyco?
AUTHOR'S EXPLANATION: lyco reduces the risk of stroke.

We can weaken by providing an alternate explanation for why the low-lyco people had more strokes (maybe they just eat less fruits and veggies, and fruits and veggies have some other ingredient that's good at avoiding strokes ... maybe the high-lyco people have some other behavior or trait that helps them avoid strokes), or we can weaken by undermining the plausibility of the author's story that lyco reduces the risk of stroke (this could potentially be evidence of high-lyco people who are getting strokes or low-lyco people who aren't getting strokes).

On Weaken (and Flaw and Nec Assump), the correct answer is more likely to deal with a DIFFERENT WAY to explain the Curious Fact, so I would primarily look at these answers initially with the mindset of, "What could be a different way to explain why low lyco people had more strokes than high lyco people?"

Correct Answer:
A

Answer Choice Analysis:
(A) YES, this was our first prediction. That parenthetical in the stimulus, to a savvy test taker, reads like one of those extra details LSAT slips in so that they have a mechanism for a correct answer later. This gives us an alternate explanation for the curious fact: people who eat lyco-rich fruits and veggies get high lyco levels from that, and they get stroke-resistant benefits from other ingredients in the fruits and veggies (not from the lyco).

(B) This strengthens, using covariance (when lyco is present, reduced stroke rate is present)

(C) This means nothing without knowing the relative prevalence of strokes among middle-aged and younger people. Given that in the real world we know that middle-aged people are more likely to have a stroke, this would strengthen, if anything (lower lyco, more strokes)

(D) This helps to explain why one group of people had higher lyco, but it doesn't point to a different explanation for why that group had lower rates of stroke.

(E) Wide variation doesn’t matter or would strengthen. The statistic we're looking at compares low outliers to high outliers, so the argument makes more sense if those low and high outliers are significantly different in terms of lyco-levels. If there was very little variation in the the study's participants, then there wouldn't be much difference between a low lyco and high lyco person, which would weaken by making it less likely that lyco-level could be a significant difference maker.

Takeaway/Pattern: This is what you hope for on a standardized test: a template they've presented a thousand times before.
X is correlated with Y.
Author concludes that X caused Y.
Correct answer to Weaken points to a third factor Z that is the real causal factor, but happens to be associated with X.

#officialexplanation

[RuonanW40]

The reason that I didn't choose A is because the stimulus didn't mention directly that those middle-aged people with high lycopene in the blood get the lycopene from fruits and veggies. It only mentioned that some fruits and veggies are rich in lycopene in parenthesis. Honestly, I don't like any of these answers, but both A and D might be justified if we put more assumptions into the stimulus, and I think A is just as bad as D.
In conclusion, I still don't understand why A is the best answer.
Anyone can explain more about this question? Thanks.

[YasmineF465]

Okay, at first I did not like A. I was like who cares about veggies and I liked D because I was like well it sucks the least but most importantly it is an alternative explanation but it does not really weaken it because the study was about older people so whether or not young people have more L does not matter.

So the stimulus says that people with LESS L have a MUCH higher chance of stoke than those with HIGH L (really weird but okay). So you need to find something that is an alternative explanation or some example that shows the same cause (L) and No effect or same effect no cause (L)

So my reasoning behind A is since those veggies have high L and other stuff you can say that the other stuff could be what causes the benefits and NOT the L.