Q13 - Medical researcher: Scientists compared a large group

[tua37884]

Okay, so the researcher says that joggers and non-joggers were nearly equal in the number of injuries they sustained during the study. As a result, the researcher concludes that stretching before jogging is ineffective in preventing injuries. This establishes a cause-and-effect relationship.

Cause: Stretching before jogging
Effect: Injured (same as non-stretching joggers)

You can weaken the relationship in a lot of different ways but answer choice (D) says that the relationship is reversed. If the joggers were injured and then starting stretching, this would weaken the researcher’s argument.

Cause: Injured
Effect: Stretch before jogging

I might be wrong but I think this is the correct solution.

[kylelitfin]

I missed this very question when I took the October LSAT and it was a question that stuck with me throughout the exam.

I agree with your cause and effect reasoning, but I think it's even simpler than that.

The researcher believes that stretching does not prevent injuries because both stretchers and non-stretchers experience the same frequency of injuries in an observational study.

D weakens this conclusion directly. The joggers are self-aware of their injury odds. Because of this knowledge, those who are more prone to injury have developed a habit of stretching.

I think the portion of the stimulus that threw me off was that I did not notice that the sample size was not controlled. That is, the scientists in this study did not take X amount of joggers and then split the group up allowing one to stretch and the other to not stretch. They merely compared existing joggers with existing habits and drew conclusions from an observation.

With that in mind, because the self-aware joggers stretch because they know they would suffer injuries otherwise shows that this observation is, in fact, false. Stretching does help prevent injuries.

I'm not sure if this will help you, or anyone else, but that's how I reasoned it when I reviewed this test.

[jlz1202]

So does D implies that the stretch group are more prone to injury and if they do not stretch, they will suffer more injury than researchers observed. So by stretching, they have already lowered injuries although the injuries incidences still seem quite high?

Could anyone please also explain why B and C incorrect?

Is C wrong because of the scope shift from "jogging injuries" in C and "(general) njuries" in the stimulus?

Is B wrong because the fact that "many" people unable to stretch would not necessarily influence the situation that half stretch and half not stretch? So it's too vague to weaken the reasoning?

I find this section is particularly difficult compared to the other LR section and LR sections in recent years...

Thanks a lot!

[kylelitfin]

Jlz1202,

"So does D implies that the stretch group are more prone to injury and if they do not stretch, they will suffer more injury than researchers observed. So by stretching, they have already lowered injuries although the injuries incidences still seem quite high?"

Precisely. Choice (D) doesn't even weaken the statement, it proves it to be completely false. Again, the group of joggers chosen is not controlled; this is an observational study. Choice (D) is essentially saying this: Joggers who are prone to injuries stretch before they jog because they know if they don't they will suffer injuries. So if the study looked at two groups of joggers: one set who stretches and the other set that does not. And if at the end of the study they suffered nearly the same frequency of injuries, it would actually PROVE that stretching prevents injuries with (D) in mind. Because their preemptive stretching equalized their rate of injury to be in line with the average jogger.

"Could anyone please also explain why B and C incorrect?

Is C wrong because of the scope shift from "jogging injuries" in C and "(general) njuries" in the stimulus? "

Exactly. This choice takes liberties with the term "injuries" used in the stimulus. Moreover, the stimulus never indicates how many joggers were injured, it merely says that the non-stretches and stretches suffered the same rate of injury. That could be 0, 1, 2 or even all of the joggers. You don't know. So knowing that "most" jogging injuries (of a limited scope: falls, collisions, and other mishaps) are not caused by stretching is completely irrelevant.

"Is B wrong because the fact that "many" people unable to stretch would not necessarily influence the situation that half stretch and half not stretch? So it's too vague to weaken the reasoning?"

(B) is wrong because again, it's completely irrelevant. What does difficulty in stretching have to do with anything? Does that mean they have to take longer to stretch? Maybe they need to perform different types of stretching? It's too general and fails to weaken the stimulus in all facets.

[iridium77]

It seems to me that C) actually strengthens the researcher's argument as it suggests that stretching has no effect (does not help to prevent) injuries...

IF if the joggers mentioned in B) were unable to adequately perform their stretches would that not prevent them from benefiting from the effect of stretching, and thereby cause an increase in the number of injuries that they would normally incur ?
It seems to me this would have the effect of bringing their injury numbers up to par with those who had not stretched at all, and thereby negate the researcher's argument... thoughts ?

[tzyc]

Just want to double check...so if those who stretch before jogging do not stretch jogging, they would have more injuries than those who do not stretch before jogging right?
And (A) is wrong because it compares both groups to the overall? (If only compare those who stretch to the overall, it'd be different?)
Or is it because of the word rate?

Thank you

[ohthatpatrick]

You are correct about (D).

If we forced the stretch-people to NOT stretch before they jog, we would presumably find out that they get more jogging injuries than the other group.

And then if we let the stretch-people stretch before jogging again, we'd see that now their injuries are about the same as the other group. (So, stretching DOES reduce their risk of injury).

(A) is wrong mostly because it doesn't relate to stretching at all, which is the essence of this argument. (A) seems to suggest that 'taking part in a study' helps to prevent injuries, since everybody ended up being better off during the study than they would have been normally. But this doesn't tell us anything about whether stretching is/isn't doing anything to help prevent injuries.

Hope this helps.

[ericha3535]

Someone please help with d.

I believe d doesn't really work.

As posters have mentioned, d is saying that people tend to stretch because they know they might get hurt while jogging.

But I could interpret this answer choice in two ways: either they know stretch helps or they believe stretch helps.

If the former case, yeah I could see it why it's correct.

But if the latter, then it's unclear: just because they conditioned to believe that stretch helps does not really indicate whether stretch actually helps.

Anybody care to weigh in? Thanks

[ohthatpatrick]

Let me put up a complete explanation:

CONC
Stretching before jogging doesn’t help prevent injuries

why?
PREM
Two groups of joggers were compared: one group stretched, the other didn’t. Similar number of injuries occurred.

Well, in the world of causality, we’re all about validating the experimental validity of this test. This basically means controlling for all other variables.

If you had two identical groups, gave one of them Pill A and the other group nothing, and they both experienced the same effects, you would conclude that Pill A did nothing.

So if these two groups of joggers are identical, then the variable of “stretching” would prove to have had no effect, since both groups experienced the same effects.

But are these two groups identical?

This is the domain of sampling flaws / analogies / alternative explanations and interpretations?

Did they jog along the same route / similar surface conditions? If one group jogged on well maintained race track and the other group jogged on wobbly cobblestone, then I wouldn’t feel good about comparing their injury rates. We introduced ANOTHER important variable: running surface.

We could come up with endless stories that would differentiate the two groups and make them seem unfair to compare.

The correct answer, (D), suggests that people who stretch first are already more prone to jogging injuries. Thus, they aren’t an “identical match” for people who don’t stretch.

Naturally, this answer doesn’t PROVE anything. It’s possible that all the joggers in the study were equally prone to injuries.

But this answer choice raises quite a bit of doubt about whether it’s fair to compare a group of habitual stretchers to a group of habitual non-stretchers.

An earlier poster was concerned about (D) talking about “they just BELIEVE stretching” helps them. This answer choice doesn’t mention anything about belief. Saying that habitual stretchers are “more prone” to injuries means that people who habitually stretch incur, on average, more injuries than those who don’t.

Another poster was worried that we were interpreting the correlation in (D) as causality. We’re might interpret it plausibly as “being prone to injuries makes people more likely to stretch beforehand”. But even if we didn’t interpret it causally (just coincidentally), it still serves the aforementioned function of disrupting the scientific method. In order for us to compare two groups of joggers who experienced the same effects and then conclude that the variable (stretching) did nothing, we have to assume that these two groups of joggers were fair to compare in terms of likelihood of jogging injury.

So even without any notions of causality, (D) gives us that the two groups were probably not fair to compare, before the experiment, in terms of likelihood of injury.

== other answers ==

(A) This doesn’t weaken, since it does nothing to keep the two groups from being fair to compare to each other.

(B) This answer might tempt some people who would say “if you had difficulty performing stretching, then did you really stretch?” But the language here isn’t tight enough to give us the impression that “experiencing difficulty stretching = didn’t stretch”. That would be too much of a …[wait for it] … stretch.

(C) This, in a fuzzy way, seems to strengthen the argument because it says that stretching would have little if any effect on most jogging injuries.

(E) This is not helpful, since we don’t know if “certain forms of exercise” includes jogging, and this answer deals with “lessening the severity of injuries”, while the conclusion deals with “preventing injuries”.

[cvoldstad]

I am still having a hard time ruling on D in favor of B here!

Argument: 2 equal groups of joggers; 1 stretches before 1 doesn't--> both incurred same number of injuries therefore---> stretching before jogging does not prevent injuries

Perhaps my background in exercise physiology is getting in the way but if one "experiences difficulty in doing the stretch" they are NECESSARILY not doing it correctly as stretching is only effective when the musculature can relax sufficiently to release the muscles (otherwise they are, by definition, NOT stretching just STRAINING)

Thus if they are experiencing difficulty they are not stretching properly and we would not expect them to reap the benefits attached to stretching!!

[ohthatpatrick]

Nice, I like getting some specialized insight!

A couple problems remain:

(B) says "many". "many" as a quantity word on LSAT is very weak because it's unspecific.

If I say "many" of my friends are Democrats, and you know me as a liberal, you'll probably think I mean 80% or more.

If I say "many" of my friends are Republicans, and you know me as a liberal, you'll probably think I mean 20% or less ... like, yeah, sure you have some token conservative friends. People can say "hey, many of my friends are Republicans!" defensively if they feel they're being pigeon-holed as a liberal.

I could say "many people die of lightning strikes each year". Cool so how many is that? What percentage of the population? WAAAAAAAY less than 1% of the population.

So 'many' means 'more than a few', but that's about all it means.

Since this was "a large group" of joggers, the idea that five of them in the stretching group weren't really stretching, by your account, you still have to explain why the other 90% or more of the stretching group who WERE stretching incurred roughly the same number of injuries as the non-stretching group.

So always beware "many" on Strengthen/Weaken because it packs very little punch. It can still be correct if nothing else is stronger, but (D) is a correlation that applies to ALL joggers, so it's way more sweeping in scope.

==

My second concern is with your technical definition of "experienced difficulty in their efforts to perform stretches" = "didn't stretch".

I get the distinction you're drawing between straining and stretching, but don't people sometimes strain themselves before a fitness coach helps them realize they're pushing too hard and explains to them that proper stretching should involve muscular relaxation?

If I started "stretching" and you could see I was really straining myself, I would be experiencing difficulty in my effort to perform a stretch, but that doesn't mean you couldn't come along and help guide me on how to properly stretch (which could lead to my properly stretching).

What if the difficulty I experienced in my efforts to perform a stretch was simply finding enough dry floorspace upon which to do my stretching?

These are some weird stories I'm generating, but I'm suggesting that "experiencing difficulty in their efforts" is still a good bit away from "difficulty = muscle strain" and "the difficulty is at no point overcome, therefore they are not at any point successfully stretching".

[greenapples]

Hi guys,

I took PT 64 couple days ago, and read over the explanations for this question.

I arrived at D somewhat differently on my second try.

Argument: equal number of people were compared in two groups-- those who habitually stretch before jogging, and those who do not. Findings show that both groups incurred same amount of injuries
Conclusion: This finding indicates that stretching before jogging does not help to prevent injury.

D shows us that the more prone a jogger is to jogging injuries, the more likely he or she is to develop the habit of performing stretching before jogging.

Wait a minute. If those who are more likely to get into injuries are the one that develops a habit... they most likely got the same amount of injuries that people w/o stretching got because of stretching!

D shows that stretching actually did help "tame" the amount of injuries that could have happened. D shows that the people that were chosen to be in that group of joggers who habitually stretch before jogging wasn't all that fair, because those were the ones that tend to get more injuries! They were probably decrease the number of injuries to be same as those who don't stretch, because they developed a habit of stretching.

What do people think?

[gaheexlee]

That's actually exactly what I thought when I read (D). (D) lets us know that perhaps the end result numbers don't convey the whole story: maybe more of the joggers who stretched would have incurred injuries had they not stretched.

A parallel example would be: a group of 100 people eat multivitamins daily and another group of 100 people don't, but there are 40 people in each group who get migraines every month, so you conclude that the multivitamins don't help with migraines. But what if the first group of 100 people didn't take the multivitamins at all? Perhaps the number of people in that group who suffer from migraines would then go up to 70.

[danielznelson]

Could "C" also be wrong due to the fact that "most" could conceivably leave as much as 49% of occurred injuries to stretching (or lack thereof)-related injuries and that, whatever the actual percentage, the number of injuries across the two groups were "roughly the same," thus indicating that stretching does not seem to prevent injuries?

In other words, there could still be many injuries NOT stemming from "falls, collisions, and other mishaps [unrelated to flexibility], yet stretching did not lessen the number of the injuries outside of the category in which most injuries occur. Therefore, stretching doesn't seem to make of a difference.

[phoebster21]

Hi There,
Can someone please help me understand what is wrong with my reasoning for A?

My thoughts:

One way to weaken an argument is to point out flaws with the methodology. If we can prove that all the ppl they observed in the study were Olympian athletes then maybe WHATEVER findings/conclusions they derived from this study simply would not hold true for the general public.

So sure, 10 olympians are being watched and 5 don't stretch before (jogging-- literally...a 3 mph activity) and 5 do. Both groups have roughly the same amount of injuries which (as answer choice A states) is LOWER than the general public.

So if, as a group, they're distinguishable from the general public in that they had a lower amount of injuries, then couldn't the results (i.e. conclusion- stretching b4 doesn't prevent injury) be thrown out?

PLEASE CLARIFY.

[ohthatpatrick]

You're not completely wrong, but that line of objection is way weaker than (D)'s, which IS still a methodological complaint.

If we're comparing two groups of joggers for the sake of seeing whether stretching makes a difference, we want to control for as many other variables as possible and make both groups as identical as we can, except for the variable of stretching.

(D) is suggesting that we haven't done so. We're comparing a group that is more prone to injury with a group that is less prone to injury.

If those two groups ending have a similar number of injuries, then something favorable assisted the injury-prone group or something unfavorable afflicted the less injury-prone group.

For (A), I don't know how to interpret "THE overall rate of jogging injuries". I don't think it means a national / global average. I think it's referring to the rate of jogging injuries for the actual joggers involved in the study.

The introductory modifier makes it seem like we're saying Group A had a lower rate of injuries during the study than Group A has normally.

So that takes your Olympian vs. average person angle off the table.

But more broadly, the second you're resorting to an exotic story involving Olympians you probably wanna think to yourself, "This is Strengthen / Weaken. Correct answers aren't bulletproof. They just increase plausibility or doubt. I shouldn't need to tell myself anything but commonsense ideas."

We could ALWAYS dream up some back story that would make an experiment lucky, tenuous, atypical, etc. But read the paragraph that starts every LR section. It says "You should not make assumptions that are by commonsense standards implausible, superfluous, or incompatible with the passage."

The idea that our "large group of joggers who do NOT habitually stretch" is composed of 5 Olympians is definitely violating that instruction.

[arya.bhaskar1987]

Actually Answer choice (C) would fit better had a study indicated that joggers who stretch had lesser injuries and had the researcher concluded that the same is attributable to the stretching. In that case (C) would surely weaken the argument, imo.

[erikwoodward10]

It finally clicked. Been looking at this question for a few days. Maybe me typing this out will help someone else understand this in the future.

A few of the explanations for D rest upon the idea that D somehow shows that stretching DOES help to prevent injuries. Logically, that would be a great way to attack this conclusion--by showing that the logical opposite of the conclusion is valid. However we can't conclude that here--even given D, we don't know that stretching actually helps to prevent injuries or not.

Given the premises and the conclusion, even when considering D as valid, it is possible that stretching does not help to prevent injuries, and by some miraculous occurrence the rate of injuries between the groups were still equal.

D is correct because it shows that the comparison itself is invalid. We need the two groups to be completely equal, all factors considered, in able to draw a valid conclusion about one variable that they both face.

So this is an interesting question because we're not weakening the conclusion very strongly--we don't have a logical opposite that PROVES that stretching DOES help. We just have a subtle point that suggests that the assumption that the conclusion is drawn upon (that the two groups are equal) is incorrect.

[fadams]

Joggers were divided into two equal groups
Group A: stretched - same effect
Group B: no stretch - same effect
Yet the effect is the same between them, and that is the same number of injuries.
Thus, stretching doesn't prevent jogging.

necessary assumption: group A and B are comparable. if they are not comparable, then this evidence doesn't have to show that stretching is useless.
strengthen (support NA): the groups are identical in every way except for stretch to begin with
weaken (attack NA): the groups are different in some way besides stretch to begin with (D. the groups are different to begin with)
flaw: fails to consider the possibility that group A and B are not comparable or presumes that group A and B are comparable

A. rate of jogging was lower than overall rate of injury for both groups relative to overall rate of jogging injuries. if you picked this, you probably thought: well since it's lower relative to everyone else this stretching could have helped with reducing injuries.... or however you justified it. But you would have made the same assumption as the author, and that is that A and B are comparable. You committed the same flaw as the author in making an unwarranted assumption.
B. in the group, some of those previously injured experience difficulty in their efforts to perform stretch. this one is about effort to perform stretch. irrelevant
C. this is about cause of injuries. irrelevant
D. the more prone a jogger is to injuries, the more likely he is to stretch.
If considered, well yea, then the two groups didn't start off the same. it is entirely possible that those injured got to the same place as those who didn't stretch by stretching, suggesting that stretching can cause the effect.
E. discuss other forms of exercise, but we don't know if it includes jogging. The conclusion specifically says "the evidence based on study of joggers indicate that stretching before jogging does not help to prevent injuries. You can't refute this by saying "well, in basketball, stretching does help reduce injuries!" You would have committed a red herring flaw, because you changed the subject of the discussion to something the author never commits to considering. On the other hand, if the conclusion is something over-generalized to something like "thus, the study shows that stretching before any physical activity does not help prevent injuries." then you can easily bring up the basketball example and use it as an overlooked possibility to weaken the conclusion, since the flaw made is an unwarranted assumption that A. the study on jogging is a good study and b. the study on jogging is representative of all physical activity. This is what I picked the first time, sooooooooooooooooooooooo =(