Logical reasoning PrepTest 125 · Section 4 · Question 20

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen

Stimulus Summary:
Most important viewer question - Will it rain?
This station - Most times we said, "Yes," we were right.
Most popular stations - Most times they said, "Yes," they were wrong.
Conclusion - This station is more useful/reliable than other stations.

Answer Anticipation:
This is a notoriously difficult question, so let's dig in to make sure we understand it!

This argument reaches a comparative conclusion—one station is more useful and reliable than the most popular stations. In order to reach a comparative conclusion, an argument needs to establish the criteria for the comparison and address that criteria for each thing being compared.

Here, the two elements of the conclusion are that the station is more useful and more reliable. Does it establish the criteria to reach that? Yep! It says that usefulness is related to the most important question for viewers in the area—Will it rain?

Since it establishes the criteria, the shortcoming must come from the way that it compares the station in question with the most popular stations. However, it's hard to see where that flaw is when you first read through it. Doesn't the argument establish that the station is right a higher percentage of the time than those other stations?

Yes. . . when it predicts rain. But that's not the only stat that matters—it also matters if they're right most of the time they don't predict rain. It might seem as if the former guarantees the latter, but that's not true. To see why, let's consider an analogous situation—rolling a regular die (singular of dice).

If you always guess that it'll come up 1, you'll be right 100% of the time that 1 comes up. However, you'd be wrong the _ of the time another number comes up.
Similarly, the station here might only predict rain when the city's already in the middle of a multi-day hurricane. In that case, they'd be right most of the time—it'll likely rain tomorrow—but there would be many, many times that they'd predict no rain when it would rain.

In short, the station is established as being right more often when one answer is given to an important question, but it doesn't establish that it's right more often when it gives other answers to that important question.

Any answer that establishes the station is also correct more often when it predicts no rain will strengthen this argument.

Answer Explanation:
Just when you thought the difficulty in this question was behind us, we get this as the correct answer. How does it address the issue of accuracy when it isn't raining? Well, the prediction will either be that it'll rain or it won't. If the meteorologist's station predicted rain more often than other stations, and it was right on most of those occasions, then it had a high level of accuracy and it also must have been relatively accurate on the days when it wasn't raining. This strengthens the argument.

Key Takeaway:
Comparative conclusions require the argument to establish the criteria for the comparison and then discuss those criteria for all things being compared. Missing either part is a flaw, and spotting that missing piece can be key to finding the correct answer.

Also, when the answer to a question is important to the argument, see if the premises provide a comprehensive analysis of potential answers. Here, failing to discuss accuracy when the answer to whether it'd rain was, "No," was the flaw in the argument.

Incorrect. There's no indication that having a meteorologist is related to making accurate predictions about rain, so this answer is out of scope.

Incorrect. While it may be popular for the investigative news reports, that doesn't tell us anything about the accuracy or usefulness of the weather reports. Those reports could be the most accurate even if people don't tune in specifically for them.

Incorrect. Is this different from other stations? Without knowing, it's hard to analyze this answer.

Incorrect. First, this answer is about all competitors, whereas the conclusion compares the meteorologist's station only to the most popular competitors. Second, this answer doesn't provide all that much information since we don't know how many other stations there are and thus how frequently any given station made the same prediction.