In an experiment, 500 families were given a medical self-help book

A: Less diseases
B: Access to Self help medical books
C: Less visits to doctor

A --> C : A general fact as stated in the last statement
B --> C: An observation as stated in passage (the average number of visits to doctors dropped by 20 percent for the families who had been given the book but remained unchanged for the other families.)

A--> B : Conclusion (As per the last statement, they think that if A leads to C and B leads to C, that means A leads to B.

This is flawed as D explains (two different states of affairs could each causally contribute to the same effect even though neither causally contributes to the other)

can someone please help with this Q

Here, both (d) and (E) are plausible

but (E) is better than D attributing some other cause for reduced disease and eliminating the given causal relationship

whereas (D) states that other than medical self help book, there can also be a 2nd factor that led to reduced visits

but this does not negate the fact that self help book was not responsible at all for reduced visits

plus we have no info to infer that the families that reduced their visits had access to this 2nd other factor

it can all be they had self help books and these books in turn reduced the visits

making (E) better


DmitryFarber
MartyMurray
egmat
gmatwhiz
ChrisLele
napolean92728

First, be careful about "better." There is one right answer, and that's that. D isn't the answer because it's better than E, but because it accurately describes a flaw in the argument, while E does not!

So why not? E is trying to address alternative causal possibilities. If we know that families that have a self-help book visit the doctor less often, which of these represents the correct causal link between having a book and visiting the doctor?
BOOK causes FEWER VISITS
or
FEWER VISITS causes BOOK
or (as E suggests)
SOMETHING ELSE causes FEWER VISITS + BOOK

The problem here is that this has already been covered by the argument! This was a controlled experiment in which people were assigned to have the book or not. It's possible that some people in the control group had a book, too, but we know that the first 500 families definitely had a book, and we know why: they had it given to them! So any answer that address potential other causes for them having the book is irrelevant.

D, however, addresses a fundamental flaw in the argument's logic. The premises give us two correlations:
BOOK --> FEWER VISITS
and
BETTER HEALTH --> FEWER VISITS

But the conclusion relies on making these into a chain: BOOK --> BETTER HEALTH --> FEWER VISITS. How do we know that's true?

Imagine that I had this:
EAT PIE --> FULL
EAT CAKE --> FULL

Clearly, we couldn't conclude that eating pie makes you full by making you eat cake (PIE --> CAKE --> FULL)!

That's what D is getting at. It's possible that BOOK and BETTER HEALTH could both independently lead to FEWER VISITS. That doesn't mean that BOOK has to lead to BETTER HEALTH.