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

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.

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.

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.

Thanks so much avigutman - the analogy really helps..I did think the 'placement' of information was not similar to the original question

Tried to create a same analogy with exact placement of information as in the original problem


Personally - C1 | C2 | C3 | C4 -- all seem right to me. They all explain why the having 'no curtains' plays NOT ROLE in JD's awakening. .

This is much better, jabhatta2. Now, can you identify something important that C1 does, making it analogous to the original C, which C2,C3,C4 don't do?

Hi avigutman - thanks for responding. - C1 ties virtual assistant to No Curtains. I see C in the original question does that too.

Not sure if its necessary to tie virtual assistant to No Curtains however.

C2 / C3 / C4 - in my view DO NOT TIE virtual assistant to No Curtains and are still passable answers.

For example -- in C2 -- the virtual assistant is very loud. C2 doesnt talk about NO curtains explicitly but because the virtual assistant itself is very loud -- i wake up.

Does C2 answer the question -- Why HAVING NO CURTAINS doesn't play a role in JD's awakening ?

Yes - because the virtual assistant is loud and because the virtual assistant is loud - i wake up

So the problem here, jabhatta2, is that JD and Avi are individuals, as opposed to populations. It's certainly possible that it just so happens JD has a virtual assistant and Avi doesn't. Just by coincidence, the guy with curtains doesn't have a virtual assistant, and the guy without curtains does have a virtual assistant. Surprising phenomenon explained. Great.

But in the original, we're not comparing two individuals. We're comparing two populations.
So, if we discover that, in general, people without curtains tend to wake up during the sunrise more consistently that people with curtains, and we discover that this is NOT due to the sunshine coming in through the window and waking them up, then C1 explains this surprising phenomenon, but C2,C3,C4 do not.