GMAT

Flaw questions are another often-seen challenge on the GMAT.  The central error in reasoning on GMAT flaw questions always comes down to the same thing: the evidence presented doesn’t logically lead to the conclusion.  You can’t argue with the evidence itself, so don’t be distracted by answer choices that directly contradict what’s stated in the argument.  However, you CAN argue with the way the evidence was obtained or interpreted, or with how it is connected to the conclusion.  Let’s look at a couple of examples:

Teenagers and young adults in their early 20s are 3 times more likely to participate in volunteer work than are men and women over 25.  Of those people who volunteer, teenagers are also twice as likely to donate more than 5 hours per week to volunteer work as are those over 25.  Thus, it must be true that teenagers are more aware of the ways that volunteer work benefits the community than are any other group of people.

Here, the problem is that the evidence as given doesn’t support the conclusion.  All of the evidence focuses on volunteer participation and the amount of volunteer work done.  But the conclusion is about recognizing the value of volunteer work.  That shift is a serious flaw; the key to recognizing that flaw is keeping an eye out for terms that appear in one part of the argument—evidence or conclusion—and nowhere else.

A recent study of teenagers in Alphaville showed that students on the Alphaville High School football team were considered by their peers to be more academically successful and of higher social status than were students in the marching band.  Therefore, Pete, a Betaville soccer player, should quit soccer and join the football team if he wants to be more popular and get better grades.

This argument has multiple flaws.  Let’s look at them individually:

1. Evidence is given only about Alphaville teenagers, but the conclusion is about a single Betaville teenager.  The applicability of evidence about one geographical area to another area is questionable, as is evidence about one small group to one single case.  A larger, more geographically relevant sample size would help here.
2. The evidence given compares football players to marching band members, but the conclusion is about a soccer player.  A conclusion about a soccer player would be better supported by evidence about a soccer player.
3. The conclusion makes a recommendation for a course of action that would allegedly help Pete be more popular and get better grades.  But the evidence only describes peers’ perceptions of football players, which might be relevant to popularity, but do not provide a solid basis for a conclusion about their grades.  Peer perceptions are not a sufficient basis for a conclusion about a numerically measurable issue like grades.

An answer choice addressing any one of these flaws would be correct.  A strong test-taker will notice flaws as he or she reads, and will be looking for an answer choice addressing one or more of the predicted flaws.  Don’t go to the answer choices without at least one prediction in mind of a pre-identified flaw; tempting wrong answer choices can easily lead you astray and cost you time or points if you let them guide your evaluation, instead of taking control and navigating actively through the answer choices.

Brianna is thinking about getting a puppy.  She would like to adopt from the local Humane Society, but she recently read an article in which owners of purebred dogs purchased from dog breeders reported a low incidence of health or disciplinary problems with their pets.  Brianna should therefore purchase her new puppy from a dog breeder.

The reasoning in this argument is questionable because it makes a recommendation based on self-reported information from dog owners.  Self-reported data can easily be weakened by the suggestion that the people surveyed lied.  More objective data is better for supporting a conclusion.  Also, the evidence given doesn’t discuss Humane Society dogs, so there’s insufficient support for concluding that purebred dogs are preferable.

Overall, the key to identifying the flaw in a GMAT question is having an understanding of common flaw types.  The general rule is that the flaw will either lie in the reliability of the evidence itself or in the terms of the conclusion that is drawn based on the evidence.  These are the things to be looking for now, and in a later blog post, we’ll give more attention to a few specific common flaw types.