PrepTest 131, Section 1, Question 4
Advertisement: Seventy-five percent of dermatologists surveyed prefer Dermactin(37 more words not shown)
The reasoning in the advertisement(5 more words not shown)
- Aoverlooks the possibility(16 more words not shown)
- Bfails to state(21 more words not shown)
- Cpresumes, without providing(13 more words not shown)
- Drelies on an(14 more words not shown)
- Eoverlooks the possibility(18 more words not shown)
Reading the argument
Seventy-five percent sounds impressive, but who was surveyed? Think about an advertisement saying four out of five doctors recommend a toothpaste. If the company asked doctors at its own headquarters, we might want to know more before treating their answers as an independent endorsement.
Here, the company also says it consulted dermatologists while developing Dermactin. Were those the same dermatologists who later said they preferred it? People who helped create a product might be attached to it. The passage does not tell us that this happened, but it is a reasonable question to ask about the evidence.
What we’re looking for
There is also a step from “these dermatologists prefer it” to “this is the best cream for you.” An expert preference can be relevant without settling every question about which product someone should use. The flaw question asks us to identify a weakness in the recommendation's support. I would look closely at what that survey actually establishes.
Working the answers
- A
Other kinds of doctors might use Dermactin, but that does not show that a survey of dermatologists is unrepresentative of the relevant expertise. Dermatologists are specialists in skin care. Merely adding general practitioners or oncologists as potential users does not identify a defect in the sample the advertisement relies on.
- BCorrect
Here is another survey problem: we never learn how many dermatologists were asked. Seventy-five percent could mean three out of four. A handful of doctors could produce the advertised percentage without giving us reliable evidence of a broad expert preference.
We do not have to establish that the survey actually used only four people. B accurately says that the missing number leaves that possibility open. The percentage sounds persuasive while concealing information we need to assess the survey's reliability.
- C
The advertisement does not compare the qualifications of different dermatologists. It never says one dermatologist is better able than another to judge the cream, so C attributes an assumption the argument does not make.
- D
The people surveyed are dermatologists, who do have special knowledge of skin care. There may be questions about the survey's size or independence, but it is not a survey of ordinary consumers with no relevant expertise.
- E
The recommendation begins “if you need a skin cream.” People who would be better off using no cream are therefore outside its stated scope. The advertisement recommends a particular cream to people who need one; it does not tell everyone to use skin cream.
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