A two-year study beginning in 1977 found that, among 85-year-old peopl

This is a paradox question and you have to explain the paradox.

- Those whose immune systems were weakest were twice as likely to die within two years as others in the study.
- But cause of their deaths was more often heart disease - something which has nothing to do with immune system

This is odd, right? If people with weak systems were the first to go, they should have gone due to some immune system related complication. But this is not so. They often died due to heart disease.

Let's look for an option that w ill explain this:

(A) There were twice as many infections among those in the study with the weakest immune systems as among those with the strongest immune systems.
If people with weak immune systems had many more infections (which makes sense), then it also makes sense that they will die due to those infections and not heart diseases. Hence, we do not get an explanation of the paradox.

(B) The majority of those in the study with the strongest immune systems died from infection or cancer by 1987.
How those with strongest immune systems died is out of scope.

(C) Some of the drugs that had been used to treat the symptoms of heart disease had a side effect of weakening the immune system.
This explains our paradox. If medicine for symptoms of heart disease causes weak immune system, it means that people with heart disease would have weak immune systems too. Perhaps those were the people that we identified with weak immune systems. They died due to heart disease is then understandable since they had heart disease (the medicine is symptomatic treatment only).

(D) Most of those in the study who survived beyond the two-year period had recovered from a serious infection sometime prior to 1978.
Out of scope. We are not worried about people who died after the two year period. We are worried about the cause of death of those who died within the two year period.

(E) Those in the study who survived into the 1980s had, in 1976, strengthened their immune systems through drug therapy.
Again, out of scope. Same reason as that of (D).

Answer (C)

A two-year study beginning in 1977 found that, among 85-year-old people, those whose immune systems were weakest were twice as likely to die within two years as others in the study. The cause of their deaths, however, was more often heart disease, against which the immune system does not protect, than cancer or infections, which are attacked by the immune system.

Green is background/ a premise, blue is more background and a counter premise
-- So this is a paradox question. Here we are given a few pieces of information: We know that immune systems help fight off bad things. But, immune systems do not fight off heart disease. Yet there is a connection between those who died and a weak immune system. How can this be? We need to bridge this gap!

Diagram: Bad system -- can't fight disease
Bad system -- XXXX -- death by heart disease

Which of the following, if true, would offer the best prospects for explaining deaths in which weakness of the immune system, though present, played no causal role?

(A) There were twice as many infections among those in the study with the weakest immune systems as among those with the strongest immune systems. -- comparing strong vs. weak immune systems. We want a reason why the heart disease occurred, so this is out.

(B) The majority of those in the study with the strongest immune systems died from infection or cancer by 1987. -- Again, no comparison or reason so this is out

(C) Some of the drugs that had been used to treat the symptoms of heart disease had a side effect of weakening the immune system. -- Bingo. This bridges the gap. This says X caused Y and thus is our needed paradox solver!

(D) Most of those in the study who survived beyond the two-year period had recovered from a serious infection sometime prior to 1978. -- Who cares about those who survived post infection?

(E) Those in the study who survived into the 1980s had, in 1976, strengthened their immune systems through drug therapy. -- This talks about strengthened immune systems, but not about a connection between heart disease and weak immune systems, so this cannot be our answer
_________________

IMO C
Here the confusion created between Immune system, heart attack and death is rightly addressed by option C, explaining the heart diseases and it's treatment is cause of decreased immunity, which however stated by arguement that it has no effect on death rate, hence answer again proved that immune system has not causal effect rather it had become weak by the side effect of heart disease treatment

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the answer is C.

We'll solve this question using the

Logical

approach, because we can gain. pretty good idea of what we are looking for by thinking of the logical structure of this argument.
We are looking for a reason that weak immune systems and death by heart disease are correlated, even though we know the former doesn't cause the latter. Well, maybe the latter causes the former? That is, maybe having heart disease can somehow cause someone to have a weaker immune system. Another option - maybe they are both caused by a third factor? Say, people who are generally sicker have both issues.
Looking over the answers, (C) is a clear example of the first option, revere causation, wherein heart disease caused the weak immune system: (C) Some of the drugs that had been used to treat the symptoms of heart disease had a side effect of weakening the immune system.

Dear moderators,

I believe this is a "Paradox" question and not a "Weaken" question. The tag should be changed... Thanks in advance!

dear GMATNinja, GMATNinjaTwo, VeritasKarishma, AnthonyRitz, CJAnish, MartyTargetTestPrep,AndrewN,VeritasPrepBrian

would you experts help me understand this CR question?
I spent lot of hours, but still cannot understand the question.

at first ,the author says: people with weakest immunity system are more likely to die,
then he says: the cause of their death. so for me, all of them are with same level immunity system, all of them are weakest immunity system
later, he says, among them, more are dead from heart diseases, which has little relationship with immunity system.
but, we have already the people died are all with same level, why the question wants a reason why immunity system plays no role.

I have no idea what I missed.

genuinely need your help.

thanks in advance

Hey avigutman - was wondering if you have space for the upcoming Saturday AMA - could you go over how you would perhaps solve this CR.

the argument seemed seemed bizzare to me

i. Why is the yellow bit given ? Doesnt the yellow bit already answer the question posted in the red question stem

Given i read the question stem first -- the yellow answered the question for me. (heart disease is the problem and heart disease is NOT IMPACTED by if you have a strong immune system or a weak immune system)

So, heart disease was the cause for these peoples deaths.


ii) i see some people are saying - this a paradox question / some people are saying --- this is a correlation / causation question.

Did you figure that out when you read the question stem or the argument. I did not.

I thought of this as a classic - strengthener question.

^^^

(iii) I wrote down on my notes


The underlined bit above is what i thought was what we needed to strengthen

I dont think i have understand the argument because option C doesnt really strengthen what I have in the underline

I think this error caused a chain reaction for you, jabhatta2, leading to your other confusions.
The question stem is asking us to explain a surprising phenomenon:
Which of the following, if true, would offer the best prospects for explaining deaths in which weakness of the immune system, though present, played no causal role?
Why does that phenomenon require an explanation?
Well, if weakness in the immune system is present in deaths (more so than its presence in comparable people who didn't die), one would expect that this weakness in the immune system is at least part of the reason for the death. To find out otherwise would be surprising, don't you agree? In other words, we have a correlation here: weakness in immune system ~ death within 2 years
And one would expect the reason for this correlation, at least in part, to be: weakness in immune system > death within 2 years
But from the question stem we know that this is in fact not the case. The argument then gives us more information about what's going on, but it doesn't explain this surprising phenomenon - it merely gives us the details about it.
Answer choice C gives us an explanation for these surprising findings.

Hey avigutman - thanks so much for responding

Here is how I thought about the argument (getting rid of extra fluff) - the answer – should be what I have listed in the red.

What I found strange is that -- Rather the ‘answer’ (in the red) is already given to me in the argument itself !

Not sure why the argument solves the riddle for me.

This is the structure for MANY CR questions (solve the riddle or give me an alternative reason for the strange phenemona)

I think it's just a matter of misunderstanding the nature of the riddle, jabhatta2.
The riddle is not what caused the deaths of those people?.
Rather, the riddle is:
If the weak immune system didn't contribute to the deaths, then why were the people whose immune systems were weakest twice as likely to die within two years as others in the study?

Thanks so much for responding avigutman.



If thats the riddle -- the answer to the riddle, is already presented to me (the yellow is the answer to the riddle). The yellow clearly solves the riddle and the yellow does not leave any gaps as far as i can see.

Am i being asked to strengthen the fact that this answer is definitively the answer to the riddle ? That maybe NOT heart disease but perhaps ANOTHER REASON (lack of excercise) is the solution to the riddle

You're going to have to walk me through how the yellow solves the riddle, jabhatta2.
What difference do you see, if any, between these two riddles?

Riddle #1:
If the weak immune system didn't contribute to the deaths, what did?
Riddle #2:
If the weak immune system didn't contribute to the deaths, then why were the people whose immune systems were weakest twice as likely to die within two years as others in the study?

Hi Avi - thank you so much for responding. If i can respond


Let’s say the answer to this riddle is – being involved in a car crash. A car crash killed them all



Don’t freak out but I think I can say - being involved in a car crash is also the answer if I can prove
- that the COMBINATION of the being involved in a car crash + weak immune system makes one TWICE AS LIKELY TO DIE
vs
- someone who was just invovled in a car crash (but a good /strong immune system)

But aren’t you ignoring a very important part of riddle #2, jabhatta2:
“If the weak immune system didn't contribute to the deaths”

To take this back to the original argument, the question stem says “played no causal role” and the argument itself stated:
“heart disease, against which the immune system does not protect”

Even if we overlook the fact that you seem to be questioning the truth of these statements, your reasoning included a very significant “IF”, which we have no reason to believe is the case:

That doesn’t really resolve riddle #2, does it?
It’s like saying: wow, that trick the magician did was incredible, how did he do it???
Well, IF magic is real, then that explains it.
Hmmm, I still have no idea how the magician did it.

Hi avigutman -
when one reads the two riddles - can one assume that a weak immune system HAS NOTHING to do with deaths ? i think we can.

My answer to both riddles (2nd attempt)

Yes, jabhatta2. This is much better.
However, with this explanation, I'm still left wondering: why is it that the people with weak immunity just happen to be chain smokers, and the people with the average/strong immunity just happen to not be chain smokers? Depending on the sample sizes, this seems like a statistical improbability. So, your explanation has created a new riddle.
Answer choice C, on the other hand, takes care of that beautifully.

Hi avigutman - can i rephrase the question stem as the following

For the purposes of this study, explain why a weak immune system DOES NOT CAUSE any deaths (i.e. is not responsible for the extra 30 %) ?

No, this rephrasing is wrong, jabhatta2. It takes us back to riddle #1. It's also wrong to say:

Why is that wrong? Well, we know from the argument that:

So the two groups are in fact NOT affected by heart disease in the same proportionality.

The surprising fact here is NOT that a weak immune system "played no causal role" in the extra 30% deaths. Why would that, in and of itself, be surprising? There are many possible causes of death.

The surprising fact is: given that the weak immune system "played no causal role" in the extra 30% deaths, why were the people whose immune systems were weakest twice as likely to die within two years as others in the study?

But, I'm just repeating riddle #2 here, so I feel like we're going in circles at this point.

Perhaps an analogy will help?

A two-year study beginning in 2019 found that every morning Avi wakes up at precisely the same time that the sun rises. The cause of Avi's awakening, however, is not the sunshine coming in through the window, since Avi has blackout blinds that are always shut and completely block out the sunshine.

Which of the following, if true, would offer the best prospects for explaining Avi's consistent, daily awakenings at precisely sunrise time, in which the sunshine, though present, played no causal role?

(C) Avi's virtual assistant is programmed to sound an alarm at sunrise every day.

Here, too, we have a correlation. The correlation itself isn't surprising. What makes it surprising is the blackout blinds. In the original argument we have a correlation between weak immune system and death - also not surprising. What makes it surprising is that the weak immune system wasn't causing the death...

So we needed some other explanation for the correlation between weak immune system and death (this is NOT the same as needing an explanation for the death). Could it be that death was causing the weak immune system? No, that's as nonsensical as wondering whether my awakening was causing the sun to rise - it defies the laws of physics.

Well, if A~B, and neither A->B nor B->A, then there's probably some third factor involved. In the original problem, that third factor is heart disease (which both necessitates drugs that weaken the immune system and causes death). In my analogy, that third factor is the virtual assistant.