Q3 - In Yasukawa's month-long study

[goldheartgal]

I can't figure out why the right answer is D instead of C. If the smaller sized birds all survived better, then a difference in age among them doesn't make any different. It seems to be right.

I think D is incorrect. Among the birds of the same age, some are small, very few are large. The smaller size survived better than the large ones.

[aileenann]

Hello there, and thank you for your question.

In this argument we are basically looking for the best answer choice to support the author's conclusion that size is probably not the factor that explains bird survival rates and that age seems a better explanation. Thus we are basically looking for an answer choice that says that age is important and size isn't.

First, let's think about why (C) is incorrect. (C) gets what we want backwards. It says that age doesn't make a difference once you control for size. But we want an answer chocie that syas that age *does* make a difference.

Now let's talk about (D). (D) says that once we control for age, size does not make a difference. This is very helpful because it goes against the very same findings that we are trying to dispute. It is saying that if Yasukawa had only studied birds of the same age but of different sizes, he would not have found the size effect he reported in his research. So it seems like his results finding a size effect were more a consequence of the sample he was working with than of a true effect.

I hope this helps. Please let me know if you have follow-up questions or comments. Thank you!

[goldheartgal]

I got it. I misunderstood the conclusion. Thank you for your kind help.

[aileenann]

Anytime

[Mab6q]

Hello there, and thank you for your question.

In this argument we are basically looking for the best answer choice to support the author's conclusion that size is probably not the factor that explains bird survival rates and that age seems a better explanation. Thus we are basically looking for an answer choice that says that age is important and size isn't.

First, let's think about why (C) is incorrect. (C) gets what we want backwards. It says that age doesn't make a difference once you control for size. But we want an answer chocie that syas that age *does* make a difference.

Now let's talk about (D). (D) says that once we control for age, size does not make a difference. This is very helpful because it goes against the very same findings that we are trying to dispute. It is saying that if Yasukawa had only studied birds of the same age but of different sizes, he would not have found the size effect he reported in his research. So it seems like his results finding a size effect were more a consequence of the sample he was working with than of a true effect.

I hope this helps. Please let me know if you have follow-up questions or comments. Thank you!

I just wanted to add that this although your explanation is great for the most part, this question is an inference question, not a strengthener. You could classify the next question, which deals with the same stimulus, as a strengthener.

[Ibrahim.diallo]

What is the best way break down this argument to its core? I often get mixed up between the LSAT author's conclusion and the author/conductor of the research. What is the best way to keep the two separate in my head?

[maryadkins]

Good question!

I would say you can think of it this way.

Sometimes you will have an author making an argument. Straight forward, and most common, this is category 1 of LR questions with argument cores. No other arguments are brought in, no outside conclusions other than the author's.

Other times, you'll have an author presenting an argument someone else made but not actually giving an opinion on whether the author thinks that conclusion is right or not. In this case, the conclusion should be pointed out to you by the author. This is category 2.

Finally, sometimes you'll have an author presenting an argument and then disagreeing with it (or agreeing with it), in which case the author's conclusion IS different from the conclusion reached by whomever he's talking about. We'll call this category 3 (and this question at hand is a category 3 question).

Your first task is to figure out which of these argument types you're dealing with.

Again, here, we are in the third category. The author presents someone else's conclusion and disagrees with it. The argument core here is:

Premise: smaller black birds are generally younger than bigger ones

Conclusion: Y's conclusion that size determines survival is probably wrong

Hope this helps clarify.

[roflcoptersoisoi]

This is an inference question, but there is a argument in the stimulus. Our task is not to critique the argument but to infer something from it.

Argument:

Premise: Small birds tend to be younger than larger birds.

Conclusion: Yasukawa's hypothesis that size determines chances of survival over a month long period is probably mistaken.

Essentially the author is saying that Yasukawa's hypothesis is probably wrong because she fails explain or refute what could be a competing hypothesis: Age and not size affects one chances of survival.

(A) This contradicts part of the stimulus, we're told that the porportion of smaller blackbirds exceeds the proportion of large ones, meaning there was a correlation between size and chances of survival in the study.
(B) This may be true we cannot infer this from the stimulus, we're told simply that smaller blackbirds tend to be younger than larger ones and that the former have a better chance of surviving than the latter, Yasukama doesn't control for age in the study so we don't know. Plus this actually contradicts the notion that size doesn't determine one's chances of survival.
(C) What? We have no effing clue if this is true, Yasukama doesn't control for size, all she does is note the correlation between the latter and chances for survival during a one month period.
(D) Bingo. Although this answer choice accounts for size which Yasukama did not, this essentially paraphrases the author's argument: That Yasukama's contention that size determines a blackbirds chances for surival is probably not correct.
(E) No, just no, I stopped reaing after "with a larger sample". We're concerned only with the control study mentioned in the stimulus.