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#4 - Advertisement: Seventy-five percent of dermatologists

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Complete Question Explanation

Flaw in the Reasoning. The correct answer choice is (B)

When an advertisement is presented in a stimulus, we should generally view its claims with some degree of initial skepticism. This stimulus states that 75% of dermatologists surveyed prefer Dermactin to all other forms of skin cream. According to the ad, this is because the makers of Dermactin consulted with dermatologists during the product’s development “to ensure…the best skin cream on the market.” This assertion incorrectly presumes that the following flawed reasoning is valid:

    Consult with dermatologists :arrow: Ensure best skin cream

The question stem asks how the reasoning in the ad is flawed. In prephrasing this answer, we might quickly consider the flaws in the author’s reasoning:

First of all, does a consultation with dermatologists really ensure the best skin cream on the market?

Second, the argument assumes that the cited dermatologists’ preferences were based primarily on the quality of the product (for example, if the surveyed dermatologists owned stock in the company which produces Dermactin, their preferences might have been based on financial considerations).

Finally, we are not told much about the survey methods. We know nothing about how many dermatologists were surveyed, nothing about the questions asked, and nothing about the comparisons made by the survey (perhaps the respondents were given only two poor options from which to choose).

Answer choice (A): The possibility that other types of physicians might have cause to use Dermactin would not necessarily render the sample unrepresentative. Since Dermactin is a skin cream, relevant opinions in this case come from dermatologists, and these are the only opinions on which the advertisement’s claims are based.

Answer choice (B): This is the correct answer choice. Without information on the number of dermatologists surveyed, there is no way to determine the validity of the claim of 75% preference among dermatologists. We would need to know the sample size in order to determine the value of the survey results. For example, if only four dermatologists were surveyed during the development of Dermactin, then a 75% preference would only represent three opinions—hardly sufficient to draw any strong conclusions.

Answer choice (C): Since the stimulus doesn’t discuss this issue, and no presumptions are suggested regarding the relative qualifications of the various dermatologists polled, this answer choice should be eliminated.

Answer choice (D): The reasoning in the stimlulus does not rely on an appeal to the opinions of consumers with no special knowledge of skin care. While the author of the stimulus does appeal to the expertise of the consulted dermatologists, there is no appeal whatsoever to the opinions of consumers, so this choice is incorrect.

Answer choice (E): The advertisement specifically suggests “if you need a skin cream, use Dermactin.” Those people who use no skin cream have been explicitly excluded, not overlooked.