PrepTest 139

Incorrect. The conclusion is based on the survey results, not the morality of underage drinking.

Incorrect. The argument concludes only that this program was successful, not that it was more successful than any alternative plan would have been, or that it was the best/most effective plan. This plan can work even if there's a better plan out there.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
Problem - Underage drinking
Solution - Make youths take a pledge not to drink until they're of legal age
Survey - Taking the pledge is correlated with not drinking
Conclusion - The pledge works!

Answer Anticipation:
This argument bases its conclusion on a survey, and any time there's a survey, we should consider a sampling flaw and a correlation/causation flaw.

Here, the sample was 17-year-olds, who would count as members of the group being targeted by the pledge. While it's possible that people of this age aren't representative of the underage group as a whole, there doesn't seem to be a huge sampling flaw here. Additionally, the results talk about those who do and don't drink, not those who report drinking or not drinking, so there's no reporting flaw there. And while the pledge taking is stated as being based on reports, there's no inherent reason to lie about that (unlike there would be to underage drinking, as most kids don't want to admit to a crime), so, while possible, it's unlikely that a reporting flaw is the issue the correct answer will highlight.

What about the correlation/causation flaw? The conclusion is based on a causal assumption—if the pledge was successful, that means that it achieved its goal of reducing underage drinking. However, it's based on a correlation—those who don't drink tended to report taking the pledge, whereas those who do drink tended to report that they didn't. It's possible, then, that something else resulted in this correlation between these two phenomena instead of the pledge itself working. For example, maybe some parents made their kids take the pledge and also implemented harsh punishments for underage drinking. If that's the case, then it's the parents who are the true cause of the correlation, not a direct causal relationship between the two.

Answer Explanation:
This answer brings up the correlation/causation flaw that was present in the stimulus. Taking the pledge was correlated with not drinking, and so the argument concludes the pledge was successful—i.e., it was the cause of those youths not drinking. However, it's possible that some other factor resulted in both refraining from drinking and signing the pledge—say, a parent who enforced both.

Key Takeaway:
Surveys tend to have sampling flaws, correlation/causation flaws, or both. Whenever an argument is based on one, check for those two flaws.

Additionally, surveys frequently have self-reporting errors—if results that require people to honestly disclose something that they would rather not, then that can skew the data. Here, however, the only data noted as being based on self-reporting was on the pledge, and there's no inherent reason for someone to lie about that. If the drinking data were based on self-reports, however, there would be reason to doubt that, as it would require these youths to admit to a crime.

Incorrect. There's no indication that anything in the stimulus was sufficient to bring about an outcome—in fact, it's suggested that some pledge-takers still drank, and some non-pledge takers didn't, showing that there were no sufficient conditions.

Incorrect. These two statements mean the same thing since they're some statements ("many" = "some"), and some statements are reversible (if many lawyers are rich, then many rich people are lawyers). Therefore, they can't be confused.