PrepTest 131, Section 2, Question 1
On the Caribbean island of Guadeloupe, a researcher(61 more words not shown)
Which one of the following,(7 more words not shown)
- AFor many of(25 more words not shown)
- BOf the healthy(24 more words not shown)
- CIn areas other(18 more words not shown)
- DThe 10 healthy(26 more words not shown)
- ESoursop, custard apple,(20 more words not shown)
Reading the argument
Did the fruit cause the disease, or did the disease change what these people wanted to eat?
The researcher found a striking association: all 35 patients regularly ate these fruits, compared with only 10 of the 65 healthy adults. But comparing the two groups doesn't tell us which way the connection runs. A disease might change someone's appetite. Perhaps atypical Parkinson's makes people crave these fruits, rather than the fruits giving people atypical Parkinson's.
What we’re looking for
So I accept the eating pattern while questioning the causal conclusion. To strengthen it, I'd like evidence connecting the fruit to the development of the disease. Maybe the fruits contain a compound that produces the symptoms. Something like that would give us more than the fact that fruit consumption and illness occur together.
Working the answers
- ACorrect
This gives us another way to investigate the connection: see what happens when patients stop eating the fruits. For many patients, the symptoms then stop worsening, and some symptoms actually diminish. That pattern supports the idea that eating the fruits contributes to the illness. It doesn't prove that the fruits originally caused every case, but improvement after removing the suspected cause makes the researcher's explanation more convincing.
- B
Trying a fruit on one occasion is different from eating it regularly. Healthy adults having sampled the fruits tells us little about the effect of the regular consumption described in the study. It doesn't connect that consumption with developing the disease.
- C
This gives us cases of the disease without the fruits. That doesn't strengthen the proposed causal connection. It also doesn't necessarily disprove it: there could be several causes of atypical Parkinson's, with the fruits responsible for some cases and something else responsible for others. Showing that the fruits aren't necessary for every case doesn't help show that they caused these cases.
- D
The healthy regular consumers ate even more of the fruits than the patients did. That is no support for blaming the fruits; if anything, it raises a further question about why heavier consumption accompanied good health. It doesn't rule out a causal contribution, but it certainly doesn't supply the missing causal evidence.
- E
This identifies something distinctive about the fruits, which can make it sound like the mechanism we wanted. But nothing connects these essential vitamins to atypical Parkinson's. We would have to add the claim that the vitamins cause the disease. A directly connects a change in fruit consumption with a change in symptoms, whereas E leaves the crucial connection unstated.
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