Comparing Comparisons, Part 1

by on November 26th, 2009

Apples and OrangesThe GMAT is in love with comparisons. In fact, one might say that the GMAT test-makers are more likely to be in love with comparisons than they are to be in love with any comparable sentence structure. See what I did there? The GMAT puts comparisons in all three verbal question types, and it does it as often as possible, which is why having a deep understanding of how comparisons work on the GMAT is a key test skill.

Why does the GMAT love comparisons so much? Let us count the ways:

  1. They are complicated to unravel and read, which makes them difficult to evaluate as answer choices. This is relevant on all three verbal sections of the test
  2. They are either right or wrong, so there is no room for ambiguity or arguments from irate test-takers.
  3. There are several different ways to make a comparison answer choice incorrect, each subtler and trickier than the next. This is primarily relevant on critical reasoning questions, but is important for some reading comprehension questions as well.

As test-takers, we are most interested in the last of these reasons. By reverse engineering comparative answer choices, Knewton has identified a number of different incorrect comparison answer choices. We hope that you will like them more than you like any comparable comparison strategies.

The members of the Lyriana city council have decided to hold a referendum about increasing sales in the underused business district of central Lyriana. Some members of the city council have proposed banning automobile traffic to central Lyriana on weekdays, claiming that this is the only re-zoning option that will reduce air pollution in central Lyriana and thus increase pedestrian traffic to local businesses. The opponents of this proposal state that automobiles are the primary method of transportation for shoppers who frequent central Lyriana, and that banning their use on weekdays will reduce the overall number of potential customers to central Lyriana businesses.

Which of the following, if true, would support the claim that the city council members’ proposal would achieve its desired effect?

So what’s at the heart of this proposal is this: that the pedestrians’ business that would be gained in central Lyriana is more valuable than the business that would be lost if automobiles were banned. This is not an easy comparison to spot by any means, and the GMAT knows it. So to make things complicated, the answer choices will include all varieties of tricky comparisons. Here are the first three:

Incorrect comparisons can compare the wrong entities:

If one or both of the two things being compared (which we at Knewton call “entities”) is incorrect, then the answer choice is wrong.

a. There are more members of the city council that support the proposal than there are that oppose it.
b. The businesses in central Lyriana are less accessible to pedestrian traffic, on average, than are businesses in neighboring business districts.
c. There are more potential customers in Lyriana that own automobiles than there are potential customers who use public transportation.
d. Small businesses in the central Lyriana business district are more likely to receive pedestrian traffic than are larger businesses in the central Lyriana business district.
e. Local customers are more likely to spend money in the central Lyriana business district than are tourists visiting central Lyriana by automobile.

Incorrect comparisons can compare the RIGHT entities on the wrong criterion:

HOW the entities are compared is just as important as WHICH entities are compared. Consider the following answer choices and how they are different from the choices above.

a. Pedestrian customers in central Lyriana pay less in transportation costs than do customers who travel to the central Lyriana district by automobile.
b. Pedestrian customers in central Lyriana tend to spend time window shopping, while customers who arrive by automobile travel to Lyriana only to buy specific items.
c. The revenue generated by businesses that cater to pedestrian customers generates more tax revenue for Lyriana than does the revenue generated by businesses that cater to customers who use automobile transportation.

A subset of the above category includes situations in which the criterion is exactly backwards; that is, those in which the comparison weakens an argument it is supposed to strengthen, or vice versa.

a. The revenue lost by banning central Lyriana customers who arrive by automobiles will far outweigh the revenue gained by encouraging pedestrian customers.
b. There are significantly more customers in central Lyriana who arrive by automobile than there are customers in central Lyriana who walk.
c. Pedestrian customers in central Lyriana spend less, on average, than do customers who arrive to the central Lyriana district by automobile.

The GMAT is chock full of answer choices like these. While at first they may seem difficult to unravel and translate, with practice, they can be spotted in a heartbeat. Of course, it helps to identify the correct entities and criterion as quickly as possible.

There are, in fact, even MORE methods by which the GMAT creates difficult comparisons. Unlike the previously mentioned comparison errors, the additional methods will have to wait until Comparing Comparisons 2: Step up 2 the Streets. See what I did there?

1 comment

  • Neat Explanation, Alex!! thanks...

    I was looking for explanation on these lines, listing out all possible options one can expect from a combo of CR argument and question stem.

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