#8 - Doctor: In three separate studies, researchers compared

[Adam Tyson]

Sometimes bringing in another study is a great way to attack an argument based on a study, if the new study tests similar things and gets different results. A good answer here might have been that another study was done that compared older children who had as infants slept with nightlights to those who had not and found no correlation between nightlights and nearsightedness. Answers A and E did bring in other studies, but not in a way that weakened the original argument - A looked at infants in the present rather than infants in the past (so the effect may not have appeared yet, if it really exists), and E looked at children older than in the first study and found "several" were nearsighted. Is that significant? How many is several? Is it enough to show the effect doesn't disappear with age? Hard to say - it might, but it might be statistically insignificant and have little to no impact on the conclusion.

In this case the best weaken is to go directly after the studies on which our author relied. By showing that THOSE studies were bad, we much more effectively and aggressively strip away all support for his conclusion. Contrary results from another, comparable study are good, when that's the best answer you have, but if you can show the studies that your guy relied on are bad all by themselves, that's even better, and we are, after all, looking for the "best" answer and not just a good one.

Thanks for asking such good questions!

[reop6780]

I finally got it! Thank you!

[SarahL]

Hi there,

The reason I eliminated E after having it as a contender between E and D was the use of the word "several" in E. To me, Several could be anywhere between 2-100. if it is really only 2 of the children, then that doesn't really prove anything. Is this a correct thought process for future questions?

Thank you!
Sarah

[Luke Haqq]

Hi Sarah!

Happy to offer some thoughts to try to provide some clarity.

To your question of whether your thought process was "correct"--in general, yes definitely. You're right that "several" could mean not very many, and in some cases, only having a small number of instances of a claimed causal relationship might not be very strong evidence for the existence of that relationship. Since we don't know whether "several" refers to 2 or 100 or somewhere in between, you'd be right in one sense to conclude that the answer therefore doesn't weaken the stimulus. However, I'm guessing it's probable that "several" on the LSAT is used like "a few," i.e., refers to at least 3. The test designers will use "some" to refer to anything more than 1.

It's also worth noting another reason that answer (E) in incorrect, namely, because the fourth study mentioned in (E) involved "100 children who were older than those in any of the first three studies." Because of this, it's not addressing the causal argument in the stimulus--it's focusing on a different study group. The results of studies done on that group mentioned in (E) don't really weaken the doctor's argument, since the doctor's argument was about eyesight effects of nightlights when introduced to a younger population.

Hope that helps!

[jrc3813]

I'm having difficulty understanding what the conclusion means. Is he suggesting that the causal relationship between nightlights and near-nearsightedness disappears as you get older? Meaning, nightlight use causes nearsightedness when you are an infant but not when you are older. Or does it mean that if nightlights caused your nearsightedness as an infant, it will disappear as you get older. If it's the first one, than D is the right answer. But I just don't see how you can draw that conclusion from these studies. They were examining three different groups of kids, and the older one's didn't show any correlation between the two. But how do you draw the conclusion that nearsightedness wears off as you age?

[Jonathan Evans]

Hi, JRC,

I'm right with you! Based on the evidence provided, how could we possibly conclude that nearsightedness wears off with age based on the evidence given? We simply don't have adequate evidence. That's the problem with the argument. That's the flaw we have to exploit to weaken the argument.

To answer your first question, as written, the conclusion is that even if sleeping with a nightlight is causally related to nearsightedness, this effect will disappear as children get older.

What evidence do we have for this conclusion? We have groups of children studied. They are different ages now, but the experiments studied whether those children who as infants slept with nightlights were more likely to be nearsighted than those who did not.

The studies with the younger children showed correlation between sleeping with nightlights in infancy and current nearsightedness.

The studies with the older children showed no correlation between sleeping with nightlights in infancy and current nearsightedness.

Based on the lack of correlation in the older children (who had slept with nightlights as infants), the author concludes that any purported nightlight caused nearsightedness likely wears off.

The credited response (D) vacates the applicability of the evidence in support of this conclusion by showing that the data were not sound.

Does this help?

[jrc3813]

Hi, JRC,

I'm right with you! Based on the evidence provided, how could we possibly conclude that nearsightedness wears off with age based on the evidence given? We simply don't have adequate evidence. That's the problem with the argument. That's the flaw we have to exploit to weaken the argument.

To answer your first question, as written, the conclusion is that even if sleeping with a nightlight is causally related to nearsightedness, this effect will disappear as children get older.

What evidence do we have for this conclusion? We have groups of children studied. They are different ages now, but the experiments studied whether those children who as infants slept with nightlights were more likely to be nearsighted than those who did not.

The studies with the younger children showed correlation between sleeping with nightlights in infancy and current nearsightedness.

The studies with the older children showed no correlation between sleeping with nightlights in infancy and current nearsightedness.

Based on the lack of correlation in the older children (who had slept with nightlights as infants), the author concludes that any purported nightlight caused nearsightedness likely wears off.

The credited response (D) vacates the applicability of the evidence in support of this conclusion by showing that the data were not sound.

Does this help?

Yes thank you this helps a lot. I didn't catch it the first time that all the studies focused on kids who used nightlights as infants. I was reading it as currently using nightlights, which is why his conclusion didn't make any sense. Got to read more carefully!

[mN2mmvf]

Hi Luke, I'm trying to understand your response that "It's also worth noting another reason that answer (E) in incorrect, namely, because the fourth study mentioned in (E) involved "100 children who were older than those in any of the first three studies." Because of this, it's not addressing the causal argument in the stimulus--it's focusing on a different study group. The results of studies done on that group mentioned in (E) don't really weaken the doctor's argument, since the doctor's argument was about eyesight effects of nightlights when introduced to a younger population."

(E) says the nightlights in that population were introduced to the children while they were infants. How is that a not a "younger population"? I thought (E) was correct because, if there are some infants who had nightlights but are still near-sighted when they're older, the effect couldn't possibly have "disappeared" with age. What am I missing?

[AthenaDalton]

Hi mN2,

The trouble is answer choice (E) is that it doesn't make any comparison between the two groups of children. We know that several of the children who slept with night-lights as children were nearsighted, but what we really need to know is if the children who slept with night-lights as children were more likely to be near-sighted than the group that slept in the dark.

In this group of 100, let's assume that 50 slept with night-lights and 50 did not. Further, let's say (for the sake of example) that 5 children in the night-light group and 10 in the no-light group were nearsighted. In such a case, it would be true that several of the children in the night-light group were nearsighted, but it wouldn't be convincing evidence that night-lights caused nearsightedness.

I hope this helps clarify things for you. Good luck studying!

Athena

[mjb514]

Can you please explain why E is wrong?