A consumer magazine surveyed people who had sought a psychologist's help with a personal problem. Of those responding...

Cindy on January 25, 2019

Answer choice B

How come B cannot weaken the argument? Pleas explain

1 Reply

Jacob on January 26, 2019

Hi @delacruzcindy4

I’m happy to help. In order to understand why B is not the answer that most seriously weakens the argument, let’s first take a look at the argument itself.

We learn from the passage that of people surveyed who sought a psychologist’s help, of those who received treatment for 6 months or less, 20 percent claimed it made things better. Of those who received treatment for longer, 36 percent claimed it made things better. And then we get a conclusion: longer treatment is more effective.

Answer B says: patients who received longer treatment were more likely to respond.

Why would that weaken the conclusion? All that an increase in response volume means is that the latter group gets a bigger sample size than we otherwise knew. But a larger volume has no impact (that we know of) on the rate of claiming that psychological help made things better. And therefore this assumption does not weaken the argument that longer treatment is more effective.

Instead, consider answer C. For this answer, we are told that patients who feel they are doing well tend to remain in treatment. This would weaken the conclusion that 6 months is more effective than shorter term treatment, because it tells us that our samples are skewed — the group that stays past 6 months feel they are doing well, and felt that way even before the six month mark!

I hope that helps. Please let us know if you have further questions.