PrepTest 142, Section 4, Question 18
Pharmacist: A large study of people aged 65–81(58 more words not shown)
The pharmacist's argument is flawed(3 more words not shown)
- Ainfers from the(13 more words not shown)
- Brelies on the(9 more words not shown)
- Cdepends on using(11 more words not shown)
- Dconfuses an effect(6 more words not shown)
- Erelies on a(4 more words not shown)
Reading the argument
Why are we using only people with insomnia to draw a conclusion about aging in general?
The study tells us that melatonin relieved most symptoms for people aged 65–81 who had trouble sleeping. That's useful information about those patients. It doesn't tell us that older people generally produce less melatonin, or that these patients' production declined because their glands aged.
Also, relieving a symptom doesn't by itself reveal the underlying problem. We shouldn't assume that anyone helped by additional melatonin necessarily had an age-related shortage. The sample already selects people with a particular sleep problem, so it may tell a different story from a sample of older people generally.
What we’re looking for
For the flaw question, focus on that jump: results from older insomnia patients are being used to endorse a broad claim about what happens as the gland ages.
Working the answers
- A
The argument doesn't infer what someone intended from an action's result. It uses symptom relief to support a claim about hormone production and aging. No conclusion about anyone's purpose is drawn.
- B
Manufacturers might have a financial interest in selling supplements, but the pharmacist doesn't simply rely on their opinion as evidence. The evidence offered is the study; the manufacturers' claim is what that evidence supposedly confirms. The sample problem remains even if every manufacturer is sincere.
- C
The argument doesn't switch between meanings of a key term. 'Melatonin' refers to the same hormone throughout. The concern is what the selected patients allow us to infer, not a change in vocabulary.
- D
The pharmacist doesn't argue that an effect caused the very thing that produced it. The problem is the move from a treatment response in a selected group to a general explanation about aging. Calling any argument about biological effects a reversal of cause and effect would miss that specific mistake.
- ECorrect
The sample consists of older people suffering from insomnia. It doesn't represent older people without that condition, yet the conclusion concerns the pineal gland's production as it ages generally. Whatever the study tells us about these patients, their sleep difficulties make them a questionable basis for that broader conclusion.
A large sample can still be unrepresentative. Adding more insomnia patients doesn't remove the selection problem or supply a comparison showing how production changes with age.
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