Thinking Like the Testmaker

Let’s say you were faced with a task: take some of the most successful 20-somethings in the world – graduates from top universities, entrepreneurs, bankers, consultants, nonprofit managers, military officers, physicians, Jeopardy champions – and write a test that challenges them immensely. But do so using content that only covers up to what they learned – and mastered – by the time they were 16. Could you make it difficult?

That’s the task that the authors of the GMAT are faced with all the time, and if you’re reading blog articles about “how to do well on the GMAT” you’re probably well aware: they’re quite good at making it difficult! How can they routinely do so? With a well-refined playbook that often takes advantage of the predictability of GMAT examinees.

In a world of “big data” the GMAT’s greatest advantage over you is that it knows what types of mistakes you’re susceptible to because it’s seen tens of thousands of students just like you. The testmakers know, for example, that GMAT examinees are bad at:

  • Recognizing when critical information has been cleverly hidden in the question stem of a problem.
  • Letting go of “idiomatic” Sentence Correction decisions that they’re unqualified to make and waiting to find decisions that they’re better at.
  • Double-checking that the number that the algebra “spit out” is actually the value that the problem requests.
  • Solving for a combination of variables all at once, instead preferring to solve for variables one at a time.

And with this information, the testmaker can return to these common themes that will lead you unwittingly to mistakes…unless you exercise the proper critical thinking. Accordingly, it’s crucial for those hoping to score over 700 that they don’t just focus on the “what” (what the question was about) but also on the “why” (why did you make the mistake you made / why was the wrong answer tempting?). Let’s consider a few examples:

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If triangles ABC and CDE are each equilateral, what is the sum of the perimeters of the two triangles?

(1) Line segment AE measures 25 meters.

(2) Side BC is 2/3 as long as side DE.

A. Statement 1 alone is sufficient but statement 2 alone is not sufficient to answer the question asked.

B. Statement 2 alone is sufficient but statement 1 alone is not sufficient to answer the question asked.

C. Both statements 1 and 2 together are sufficient to answer the question but neither statement is sufficient alone.

D. Each statement alone is sufficient to answer the question.

E. Statements 1 and 2 are not sufficient to answer the question asked and additional data is needed to answer the statements.

The testmaker’s playbook here contains two extremely powerful tools:

  • Asking about a combination of variables (“the sum of the two perimeters”) trips up people who prefer to solve for each variable (either each individual side, or each individual triangle) alone.
  • People greatly prefer using both statements together when one quickly and clearly removes any and all doubt from the “sufficient, but not obviously so” other statement.

For that reason, over 57% of users select “trap” answer C on this problem, and less than 40% answer correctly.   Statement 1 alone is indeed sufficient:

Since the sum of the perimeters is 3(one side of ABC) + 3(one side of CDE), and statement 1 gives you one side of ABC plus one side of CDE, you can just multiply that sum of 25 by 3 to now have the sum of the two perimeters. But note what you don’t have: you don’t have the perimeter of either triangle alone. And that – particularly when statement 2 gives you the ratio between the two triangles to help you determine how those perimeters will look individually – is enough to give people just enough trouble that they dive for the security of both statements together. Simply put: if the problem asks for a combination of variables, it’s highly likely that it’s easier to solve for that combination directly than to solve for the individual components separately.

Note that on this problem the “math difficulty” isn’t very high. The hardest definition is “equilateral triangle” and that’s not particularly challenging for a graduate student. The real difficulty comes from the test knowing how you’ll react: you’ve spent a lifetime as a step-by-step thinker, so it’s hard for you to jump straight to the answer when you can’t fill in the steps individually. When you make those mistakes in practice, beware! That awareness is going to help you on test day.

Consider this next example, this time from the GMAT’s verbal side:

Immanuel Kant’s writings, while praised by many philosophers for their brilliance and consistency, are characterized by sentences so dense and convoluted as to pose a significant hurdle for many readers who study his works.

A. so dense and convoluted as to pose

B. so dense and convoluted they posed

C. so dense and convoluted that they posed

D. dense and convoluted enough that they posed

E. dense and convoluted enough as they pose

Here the testmaker’s playbook includes two very common principles:

  • Recognize that people read left to right and top to bottom, so give them the appearance* of a mistake toward the left hand side of the underline / answer choices early in the set of answers, and fix that in another answer choice while subtly adding a new mistake.
  • Hide the correct answer behind a lesser-used but still correct idiomatic structure, daring people to make their decision based on what “sounds right” or on how they’d write it.

For those reasons, over 52% of users select the “trap” answer C here, whereas less than 40% correctly answer choice A. People don’t love the (valid) expression “so dense and convoluted as to…”, much preferring the more-common “so dense and convoluted that they…”. But each of those structures is correct; the testmaker just knows that, by “correcting” a perceived mistake from the upper left hand corner of the answer choices (the beginning of choice A) she can get people to make their decision on answer choice C without ever looking at the much-more-manageable decision between present-tense “pose” and past-tense “posed” on the right hand side. Since it’s illogical to think that these sentences would have stopped posing a challenge (posed, past tense), choices B/C/D are all definitively wrong based simply on that decision point that many test takers never get to.

So learn this: on Sentence Correction problems, prioritize the clearer, more-common differences between answer choices! You don’t have to decide on A vs. B before you get to the other answer choices; instead, look for where you’re most able to find a decision you’re crystal-clear on.

And more generally, keep in mind that on most GMAT problems in the 700+ difficulty range, what makes the problem difficult isn’t necessarily that the content of the problem (equilateral triangles, present vs. past tense) but rather the devices the GMAT testmaker uses to play to your weaknesses. So as you practice and (undoubtedly) make mistakes (it’s going to happen), pay attention to the reasons that you fell for trap answers. Train yourself to Think Like the Testmaker, and you’ll see right past the difficulty that your competitors never notice, and subsequently fall for.

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