Q17 - A 24-year study of 1,500 adults

[ohthatpatrick]

Question Type:
Explain the Discrepancy (EXCEPT)

Stimulus Breakdown:
Fact 1: a 24 yr study of 1,500 adults showed a big correlation between eating beta-carotene rich foods and lowering risk of cancer.
Fact 2: a 12 yr study of 20,000 showed no correlation between eating beat-carotene supplements and lowering risk of cancer.

Answer Anticipation:
GIVEN THAT one study had a big correlation between eating BC-rich foods and lowering cancer,
WHY IS IT THAT another study showed no correlation between eating BC supplements and health benefits?

Correct Answer:
D

Answer Choice Analysis:
(A) This helps explain why the people eating FOODS had a lower risk of cancer but the people eating SUPPLEMENTS did not.

(B) This explains why people in the 12 year study didn't show benefits but people in the 24 year study did.

(C) This helps explain why the people eating BC FOODS got more benefit than the people eating BC supplements.

(D) YES! This does absolutely nothing. Presumably, most well conducted studies have some control group, so this isn't telling us anything new.

(E) This helps explain why people in the 24 year study had a lower risk of cancer (not as many cigarette smokers). According to this answer, it wasn't really the beta-carotene doing much (or anything), it was the lack of smoking cigarettes. Or you could understand it as the beta-carotene DOES do something, but in group 2 where there were many more cigarette smokers, the health benefit of the beta-carotene was offset by the health detriment of smoking.

Takeaway/Pattern: On Paradox-EXCEPT questions, we have to stay very flexible to process different ways of resolving the paradox. (A) and (C) were "foods vs. supplements". (B) was "24 years vs. 12 years". (E) was "few smokers vs. lots of smokers". All the effective answers introduce or use a distinction between the two groups. The irrelevant answer introduces no distinction.

#officialexplanation

[chiefpt]

AB and C were easy to eliminate. I chose E because I didn't see how a comparison within one study could explain the discrepancy with another study.
With D I didn't see how the placebo could resolve the discrepancy. Any help would be appreciated.

[ohthatpatrick]

Even though Resolve/Explain questions are normally pretty straightforward, Resolve/Explain EXCEPT questions are often very hard! (plus this is a #17, so it's in the hardest part of an LR section)

The initial paradox was
24-year study makes it look like beta-carotene helps lower risk of cancer
YET
12-year study makes it look like beta-carotene doesn't have an effect on cancer risk

Like you said, A, B, and C are pretty easy ...
They all protect the idea that beta-carotene helps lower the risk of cancer, and they help explain why the 12-year study didn't show the same results.

However, we could have resolved this paradox the other way as well ... we could protect the idea that beta-carotene DOESN'T have an effect on cancer risk, in which case we'd have to explain why the 24-year study makes it look like it does have an effect on cancer.

That's what (E) does, and that's what the trickiest answer on these EXCEPT versions of "Explain an Unexpected Result" often does. It flips the script of which idea is more or less the given, and which idea is the Unexpected Result.

So assume for a second that the 12 year study got it right: beta-carotene has no effect on cancer risk. Well, then why did the 24-year study think it did?

Because, the people who were eating more beta-carotene were disproportionately nonsmokers. The people who were eating less beta-carotene were disproportionately smokers. So the results of the study were really just showing that smoking increases your risk of cancer (and the beta-carotene aspect was just coincidental).

Very tricky. Once you're brain has started believing the 24-year study was right, you're looking for ways to explain why the 12-year study got it wrong.

And like you said, (D) doesn't help at all. So what if half the group got a placebo? The paradox doesn't care about any placebo takers. It only cares about the people who WERE taking beta-carotene supplements who didn't see any lessened cancer risk. This answer tells us nothing new about them.

Hope that helps.

[gabcap1]

Even though Resolve/Explain questions are normally pretty straightforward, Resolve/Explain EXCEPT questions are often very hard! (plus this is a #17, so it's in the hardest part of an LR section)

The initial paradox was
24-year study makes it look like beta-carotene helps lower risk of cancer
YET
12-year study makes it look like beta-carotene doesn't have an effect on cancer risk

Like you said, A, B, and C are pretty easy ...
They all protect the idea that beta-carotene helps lower the risk of cancer, and they help explain why the 12-year study didn't show the same results.

However, we could have resolved this paradox the other way as well ... we could protect the idea that beta-carotene DOESN'T have an effect on cancer risk, in which case we'd have to explain why the 24-year study makes it look like it does have an effect on cancer.

That's what (E) does, and that's what the trickiest answer on these EXCEPT versions of "Explain an Unexpected Result" often does. It flips the script of which idea is more or less the given, and which idea is the Unexpected Result.

So assume for a second that the 12 year study got it right: beta-carotene has no effect on cancer risk. Well, then why did the 24-year study think it did?

Because, the people who were eating more beta-carotene were disproportionately nonsmokers. The people who were eating less beta-carotene were disproportionately smokers. So the results of the study were really just showing that smoking increases your risk of cancer (and the beta-carotene aspect was just coincidental).

Very tricky. Once you're brain has started believing the 24-year study was right, you're looking for ways to explain why the 12-year study got it wrong.

And like you said, (D) doesn't help at all. So what if half the group got a placebo? The paradox doesn't care about any placebo takers. It only cares about the people who WERE taking beta-carotene supplements who didn't see any lessened cancer risk. This answer tells us nothing new about them.

Hope that helps.

Thanks for the explanation. However, I was hesitant to pick E because we don't have any information about cigarettes causing cancer. I know we can assume some reasonable information about the work when reading a question, but this struck me as a leap...

I'm also confused about why the use of a placebo group in (D) doesn't resolve the argument. Wouldn't it simply prove that beta-carotene supplements have no impact on adults' health, thus explaining the difference in results?

[eds556]

I know this is out of context but what is a DE-Premis booster. I was looking at other questions and they are always wrong. Does this mean for every question, a answer that goes against the premise is wrong?