In a new police program, automobile owners in some neighborhoods whose cars are not normally driven between 1 A.M. an...

shunhe on June 30, 2020

Hi @dkl6bg,

Thanks for the question! So let’s take a look at this stimulus. Here, we’re told about a new police program where people can display a decal in their car windows, which lets police stop cars without another reason during the night to check the licenses. As a result, theft rate of cars with the decals is lower than the overall theft rate in those neighborhoods.

Now we’re asked to find a question to help us evaluate the argument’s conclusion, if the conclusion is that automobile theft has been reduced by the program. You should be able to pre-phrase a couple of questions that might help with this before you go into the answer choices. For example, it would be nice to know about the theft rate of the cars that don’t have the decals (since the conclusion is about automobile theft in general). If it’s gone up, it’d weaken the conclusion; if it’s gone down, it’d strengthen the conclusion. Just think up one or two things that might be helpful and then move on, no need to spend too much time on it.

For this question, that pre-phrase isn’t correct. And we can see the correct answer for this is (A) when we read it. The question is: are owners who are cautious enough to join the program taking other special measures to protect their cars against theft? This helps us evaluate the argument because it talks about another possibility that would explain the lower rate: other things that the owners are doing. And we can tell that this is the right answer because the answer to this question helps us strengthen or weaken the conclusion. If the answer’s yes, then it weakens the conclusion, since it might be the other stuff the owners are doing that’s making their cars stolen less, and not the police program itself. If the answer’s no, then it strengthens the conclusion by getting rid of alternative explanations. And so (A) is going to be the correct answer here.

(C), on the other hand, isn’t relevant because it doesn’t help us to know if cars are sometimes stolen during the day. If the answer’s yes or no, it doesn’t affect what we think about this decal program changing the theft rate at nights. So we can eliminate (C).

Hope this helps! Feel free to ask any other questions that you might have.