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

Question

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.

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.

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

(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.

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

(E) Those in the study who survived into the 1980s had, in 1976, strengthened their immune systems through drug therapy.

ID: 500237

KarishmaB · Accepted Answer

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)

nightblade354 · Answer

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

DavidTutorexamPAL · Answer

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.

jabhatta2 · Answer

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.

avigutman · Answer

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.

jabhatta2 · Answer

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)

avigutman · Answer

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?

jabhatta2 · Answer

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

avigutman · Answer

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?

jabhatta2 · Answer

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)

avigutman · Answer

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.

jabhatta2 · Answer

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)

avigutman · Answer

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.

jabhatta2 · Answer

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 %) ?

avigutman · Answer

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.

jabhatta2 · Answer

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. .

avigutman · Answer

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?

jabhatta2 · Answer

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

avigutman · Answer

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.

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

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