PrepTest 148

Incorrect. The data is based on looking at accident rates from the past, not assuming that a change will have an effect in the future.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
Stat 1 Ð 1/2m flights strays from its path on the runway, based on flight reports required of all pilots
Stat 2 Ð 1/20k flight strays from its path on the runway, based on partial review of air traffic tapes
Stat 1 is more reliable, so we can build runways closer together

Answer Anticipation:
This argument concludes that one statistic is more reliable than another ("so is relatively unreliable"), so we should check out the reasoning for that to see if there's any issues with the argument.

There, the Administrator argues that the first statistic is more reliable because it's based on a "thorough review" of flight reports that get filed by the pilots for "all" commercial flights. This is compared to a "partial review" of air traffic control tapes. So the Administrator is relying on that "thorough review" of "all" reports as being more reliable than a "partial review."

Is there any reason to believe that this isn't the case? Sure—if there's something that makes the air traffic reports more reliable, then even a partial review might show better data than a thorough review of data that is less reliable. And in this case, there's a reason to believe that the reports from the pilots are unreliable—they're analyzing their own flying skills. There's an inherent bias in reporting on whether you "stray[ed] off course while landing"—you'd probably want to say that you didn't! Since there's reason to question the reliability of that self-reporting/self-analyzing data, the conclusion that the other set of data is more unreliable is flawed.

Answer Explanation:
The argument relies on the reports from the pilots over the reports from the air traffic controllers in reaching its conclusion. Since the reports are about the pilots' flying and mistakes they made while landing, there's a reason to believe that this self-reported data is unreliable. This answer highlights that flaw.

Key Takeaway:
When the source of data is provided, always check to see if there's any way that data could be wrong or biased. Frequently, you'll find that the sourcing is provided to hint at a reason that it could be skewed.

Incorrect. The stimulus questions the accuracy of the results of the "partial review," not anyone's integrity.

Incorrect. The Administrator doesn't claim that the tapes are individually inaccurate—just that there was only a partial review of them and so they're less accurate than a full review of another data set.

Incorrect. This is describing an absence of evidence flaw. Since the Administrator offers her own evidence supporting the alternative number, this flaw isn't present—it requires the argument to rest solely on a deficiency in the opposing point.