Q19 - A Recent Study showed that immune system blood.

[mcb220]

I was able to get this question right through process of elimination. However, I wasn't sure why (c) was correct.
This is my general understanding:

Lets assume that before the study, all participants had a response time of 10 Seconds.
Then from the stimulus we are told that Tea Drinkers took half as long to respond to germs as did Coffee Drinkers.

So Tea Drinkers would now have a response time of 5 Seconds
whereas, Coffee Drinkers would have a response time of: ????

Now, if we negate (c) isn't is possible that even if response time of Coffee drinkers doubled, (from 10 to 5 seconds), that "Drinking Tea STILL boosted the participant's immune system?"

I do not see how negating (c) destroys the conclusion.

[dellara94]

The study only compares tea drinkers to coffee drinkers, but the conclusion is not about tea drinkers relative to coffee drinkers, but an absolute effect created by tea.

So let's negate answer C

Drinking coffee did cause the blood cell response time to double

This ruins the argument because if the normal blood cell response was 10 seconds, then those who drank coffee had blood cell responses that occurred in 20 seconds. So even if those who drank tea but not coffee took half as long as those who just drank coffee (10 seconds), then did drinking the tea really boost the participants immune system defenses? No. It didn't affect it at all.

[ohthatpatrick]

Great response! Let me put a complete one up here for posterity.

Question Type: Necessary Assumption

Task:
Which answer choice, if false, most weakens the argument

ARGUMENT CORE

conclusion
Drinking tea boosted people's immune system

evidence
In a study, people who only drank tea took 1/2 as long to respond to germs as did people who only drank coffee

ANALYSIS

Since our goal with the correct answer is to negate it and see if it would weaken the argument, we should think through how we could debate this author.

"How could we argue that tea did NOT boost their immune defenses?"

With any study where we're comparing two groups based on some experimental variable (tea vs. coffee), we have to ask the underlying questions of any good science experiment:

Were these groups equivalent, other than which drink they had? Were there any differences between the tea and coffee group in terms of initial health / age / fitness / history of drinking tea vs. coffee, etc.?

In order to judge the "1/2 as long response time" as a direct effect of tea vs. coffee, we have to control for all these other variables.

As it will turn out, the correct answer is not rewarding these usual LSAT pressure points, but a veteran LSAT student should have them on her radar.

ANSWER CHOICES

(A) If some participants drank tea AND coffee, would that give us a way to argue that tea didn't boost the immune system?

No. The study may have had lots of different groups: tea only, coffee only, tea+coffee, neither. No matter what, there WAS a tea only group and there WAS a coffee only group, and there WAS a significant difference between them in immune response time.

(B) If coffee DOES have other health benefits, does that let us argue that tea didn't boost the immune system? Definitely not.

(C) If coffee DID cause blood cell response time to double, does that let us argue that tea didn't boost the immune system? Hmmm. It's weirdly mathy. Drinking coffee meant cell response time was twice as fast as normal. Drinking tea was 1/2 as long as coffee. So drinking tea was normal response time. Oh! So drinking tea did NOT boost the immune response. The tea-only group just had a normal response time.

(D) This looks like the sort of study-shenanigans we were thinking about before. But this is about coffee drinkers and tea drinkers in general, and the conclusion is just about the study participants' (we don't even know if they WERE coffee/tea drinkers to begin with)

(E) Extreme alert. "ANY chemicals"? If coffee and tea DO have at least one disease-fighting chemical in common, does that help me argue that drinking tea did NOT boost immune response time? Definitely not.

The correct answer is (C).


This is an oddly mathy Necessary Assumption they came up with. The general tools that would help most people here would be

1. Focus on negating the answer and seeing if you can argue the Anti-Conclusion.

2. If you were really sharp in debating the argument up front, you might have thought, "Wait a sec --- all this study would show is that tea is better for your immune response than coffee. The conclusion is saying that tea is better for your immune response than NORMAL. But the study didn't say how tea/coffee compared to someone who drank neither. Maybe tea and coffee BOTH compromise your immune system, but coffee just messes it up more.

That type of thinking would make us more warm to the idea that (C) is selling us.

#officialexplanation

[contropositive]

coffee


(D) This looks like the sort of study-shenanigans we were thinking about before. But this is about coffee drinkers and tea drinkers in general, and the conclusion is just about the study participants' (we don't even know if they WERE coffee/tea drinkers to begin with)


2. If you were really sharp in debating the argument up front, you might have thought, "Wait a sec --- all this study would show is that tea is better for your immune response than coffee. The conclusion is saying that tea is better for your immune response than NORMAL. But the study didn't say how tea/coffee compared to someone who drank neither. Maybe tea and coffee BOTH compromise your immune system, but coffee just messes it up more.

That type of thinking would make us more warm to the idea that (C) is selling us.

Hi Patrick,
Would D be correct if it did not say "in general"? I was debating between D and C because the conclusion was a causation and I wanted to prove nothing else would cause the boost in the immune system.

Also, will you please elaborate on your 2nd point. I don't understand what you mean by "The conclusion is saying that tea is better for your immune response than NORMAL."

thank you

[maryadkins]

The problem is that if you negate (D), even without the "in general," it doesn't hurt the argument: coffee drinkers ARE more likely to exercise and eat healthily than tea drinkers.

Hmm. Okay. Well, in that case, tea must REALLY be improving the immune system!

See how negating it could even strengthen it? When an answer choice, negated, either has no bearing or even arguably STRENGTHENS an argument, it cannot be a necessary assumption.

[seychelles1718]

The problem is that if you negate (D), even without the "in general," it doesn't hurt the argument: coffee drinkers ARE more likely to exercise and eat healthily than tea drinkers.

Hmm. Okay. Well, in that case, tea must REALLY be improving the immune system!

See how negating it could even strengthen it? When an answer choice, negated, either has no bearing or even arguably STRENGTHENS an argument, it cannot be a necessary assumption.

What if D said, "the paticipants who drank coffee but no tea were no more likely to exercise and eat healthy than are tea drinkers." ?

Or said, "the particiants who drank tea but no coffee were no more likely to exercise and eat healthy than are tea drinkers." ?

Wouldn't these point out that other possibly influential factors were controlled in the study, which is necessary to draw a valid conclusion by comparing two groups in an experiment?

[ohthatpatrick]

The 2nd one works but not the 1st one.

(D) would be fine if it said
"The strictly coffee drinkers in the study were not less likely to exercise and eat healthily than were the strictly tea drinkers in the study."

Or if said
"tea people were not more likely than coffee people"

We can weaken this argument by supplying an alternate explanation for why the tea drinkers had better immune systems than did the coffee drinkers:
the tea people exercised more, ate better than the coffee people did

That means that a necessary assumption would rule out that idea.

Coffee people WEREN'T less exercise, worse diet
Tea people WEREN'T more exercise, better diet