A researcher discovered that people who have low levels of immune

Classical flaw of Post Hoc Ergo propter Hoc.
Only answer E weakens it.

In my opinion:
Not A because, even though there is one year pilot study, this statement is not effecting negatively to the results of the study.

Not B, because, there can be two results. Medications could result in high or low immune system. so it can either strengthen or weaken the argument.

Not C, because, this a close one, high immune system should yield high score but results are only normal. so it is a weakener but is it strong enough?

Not D, out of scope.

E, because, it is not immune system that is causing the mental illness but it is the stress that is causing the mental illness and the result of which is low immune system. Perfect!

My POE:

A) No idea how this is relevant

B) This would be the correct answer if the answer had said that the immune system IS affected by the use of medications. If it is not affected, than it actually strengthens the claim.

C) Not relevant

D) Not relevant

E) Correct, this is saying there stress causes mental illness FIRST, and then that leads to a decreased immune system. Not the claim that a decreased immune system leads to mental illness.­

Lower level of immune system --> ( leads to ) lower levels of mental health : Statement

for weaken it

E is straight forward in reverse way

high levels of stress --> mental illness --> decreased immune-system activity

A researcher discovered that people who have low levels of immune-system activity tend to score much lower on tests of mental health than do people with normal or high immune-system activity. The researcher concluded from this experiment that the immune system protects against mental illness as well as against physical disease.

Breaking the stem:
1. Low immune then low score,
2. High immune then high score.

Conclusion: Immune decides the score
For weakening CR, prove that there is some other cause leading to the conclusion, or there is a reverse relationship.
Answer analysis:

(A)there was a one-year delay between the completion of a pilot study for the experiment and the initiation of the experiment itself
Not in scope. The study duration and all is not a matter of concern.

(B)people's levels of immune-system activity are not affected by their use of medications
Not in scope. There is no use in saying that medication is the cause of such results.

(C)a few people with high immune-system activity had scores on the test of mental health that were similar to the scores of people who had normal immune system activity

Again we are concerned with Low and high/medium, not medium and high.

(D)people who have low immune-system activity tend to contract more viral infections than do people with normal or high immune-system activity

But how one can relate viral infection with a low score in mental health?

(E)high levels of stress first cause mental illness and then cause decreased immune-system activity in normal individuals[/quote]

Yes it provides an alternate explanation to the findings. E is the correct answer.

A researcher discovered that people who have low levels of immune-system activity tend to score much lower on tests of mental health than do people with normal or high immune-system activity. The researcher concluded from this experiment that the immune system protects against mental illness as well as against physical disease. OG

The researcher's conclusion would be most seriously weakened if it were true that

(A) there was a one-year delay between the completion of a pilot study for the experiment and the initiation of the experiment itself

Irrelevant.

(B) people's levels of immune-system activity are not affected by their use of medications

This strengthens the argument. If we can rule out medications as a factor that causes low levels of immune activity and hence causes people to perform poorly on mental health tests, then we can be more confident in the conclusion. Thus, we can be more assured that those test results are valid.

(C) a few people with high immune-system activity had scores on the test of mental health that were similar to the scores of people who had normal immune system activity

No. A relevant comparison (that would serve to weaken the conclusion) is that people with high immune system activity had comparable scores to those with low immunity. The comparison is between low vs normal/high.

(D) people who have low immune-system activity tend to contract more viral infections than do people with normal or high immune-system activity

OK – this is certainly true, but this choice does not weaken the key link between the premise and conclusion. The premise is that low immunity leads to lower scores on mental health (compared with those with normal or high immunity). From this, the author concludes that the low immunity is protective against diseases.

(E)high levels of stress first cause mental illness and then cause decreased immune-system activity in normal individuals

Correct! We have here the presence of a third factor which shows that the current causal chain is wrong. It’s not that people have low immunity and then score poorly on mental health tests and ultimately as a result of their poor immunity go on to be more susceptible to physical and mental health abnormalities. Rather, the mental health issues were caused by stress and that led to impaired immunity.

Hi Experts,

Is this argument an example of causal passage? Because in premise, the author is discussing "test of mental health" and in conclusion, it is about "mental illness"

Hi AjiteshArun GMATRockstar dcummins

One comment please:
If in case of absence of option E, could C be correct answer in similar question? I feel option C weakens a bit.

Yes, The 2 categories are not what we actually need to compare: low immunity vs high or normal immunity. But if there is some similarity in high and normal, would it be wrong to imagine that such case may exist between lower and other category? (means: if score of high or normal could be same , there maybe possibility that some people with lower immunity could have also high score, so is it wrong to say that people of low immunity could have similar score on the test of mental health that were similar to the scores of people who had normal or high immune system activity.

please give your opinion. AjiteshArun GMATRockstar dcummins


thanks!

mSKR, I realise you need an expert reply but see if this helps in the meanwhile -

I wouldn't agree that C is a weakener as it talks about only a few people out of the entire high immune-system activity group. There are always some or the other exceptions within every study. Moreover, the option says that the scorers were similar. Of course it's possible that if this correlation exists, somebody on the higher end of the normal immune system group would have "similar" scores to the someone on the lower end of the high immunity group.

If C somehow happens to be the best choice in such a question, it wouldn't be a good quality question IMO.

So according to CR Bible here are some of the ways to weaken a stem -
1) YOU CAN SHOW THAT EITHER A CAUSES B
2) OR THAT EITHER B CAUSES A
3) OR EITHER C CAUSES BOTH A & B

This question uses the third option. There is some other factor that is mentioned in option E the so called 'stress' that is responsible for causing both mental illness and decreased immunity

CONCLUSION - Immune system protects against both mental illness and physical illness

GIVEN THAT - People with low immune system tend to score lower on the tests of mental health than people with high level of immune system

ASSUMPTION/WEAKNER - What new information would reduce the belief in the conclusion?

ANSWER CHOICE ANALYSIS -

A) Initiation of experiment does not affect the conclusion
B) Effect of medications does not relate to the conclusion
C) Comparison of high immune system and normal immune system people has been done, whereas the conclusion talks about the people with low levels of immune system
D) Viral infections does not relate to the conclusion, conclusion talks about mental illness
E) CORRECT - It says that high stress levels causes mental illness and further results in low levels of immune system, low level of immune system does not affect the mental illness.

Weakener for conclusion?

Eliminate options A,B and C since these mention factors that are irrelevant and moreover deviating points from the stated passage. Pilot study medication and scores do not affect the reported data in the passage.

D is correct in terms of the passage but is not a weakener for the conclusion.

E mentions that stress causes mental illness and that further reduces immunity. This point weakens the conclusion since it mentions a factor (stress) that causes mental illness which is in total contradiction with the conclusion of the passage.