GMAT Tip: Proficiency in Data Sufficiency--Part I

Photograph by Charles Gullung/Corbis

This tip on improving your GMAT score was provided by David Newland at Veritas Prep.

Do you need help diagnosing your own data sufficiency difficulties? Problem Solving questions have a logical order of their own, but the consistent nature of the answer choices in Data Sufficiency can be used to help you understand why you are missing too many of these questions. You did not just “miss” a question on data sufficiency; you made a particular kind of error you can absolutely watch for, and hopefully avoid, in the future.

The two mistakes in data sufficiency are:
1) Thinking you have enough information when you really do not.
2) Thinking you do not have enough information when you really do.

The first of these mistakes can be thought of answering “too high” on the Order of Answers and the second mistake is answering “too low.”  The Order of Answers is “D then A or B then C then E.”  Consider them on this chart, ranked by “usefulness of the statements”:

D     (“I can solve this problem with either piece of information”)
A or B     (“I can solve this problem with one piece of information but only this one”)
C     (“I can solve this problem, but only with both pieces of information”)
E     (“I cannot solve this problem with this information”)

The “higher” you are on the list the more you are accomplishing (or claiming that you can accomplish) with the available information. The “lower” you are on the list means you are accomplishing less with more information.

Choice D represents doing the most with the information given—each statement is sufficient on its own—and in this way is considered to be the “highest” of the answers. Choices A and B are the next highest, since at least one of the statements is sufficient alone. Choice C comes next, since you need both statements together, and Choice E comes last, since this represents not being able to get a definite answer at all. So D is the “highest,” then A or B “next highest,” then C, and finally E.

How can you use this chart to your advantage? There are several ways, which you’ll read about in the next few installments of this three-part series. But most importantly, recognize this—GMAT questions are often written with two things in mind, a “trap” and a “reward”—the trap there to catch those not thinking as effectively as they should, and the reward there for those exhibiting the most effective thought processes.  So when you select a Data Sufficiency answer choice, particularly if that choice comes to you quickly or “easily,” it’s a good idea to check up one level (“could I have used less information to accomplish more?”) and down one level (“or is there something I’m missing that would require just a little more information to be absolutely sure here?”).  At the very least, this chart can help you double-check your work to avoid the trap and snatch the reward. For more on how this style of thinking can help you, check back soon for Part 2.

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