“Layering” in Sentence Correction Questions
By Chris Ryan
We all know that the GMAT is a computer adaptive test, and computer adaptive tests give us questions based on the difficulty level that we earn as we take the test. How do the test writers at ACT (the organization that writes the GMAT; it used to be ETS, but ETS lost the contract to ACT 4-5 years ago; GMAC manages the algorithm and owns the test) determine which questions are harder than others?
First, ACT engages in a process called normalization, wherein all freshly written questions are tested by actual test takers to determine what percentage answer the questions correctly (we know these questions as experimental questions). If too many people answer correctly, the question may need to be toughened up. If too few people answer correctly, the question may need to be dumbed down. ACT is looking to assemble a pool of questions that covers a range of difficulty, from cakewalk to mind-bending, and the test takers help them do so.
How does ACT find these test takers? Easy. Everyone who takes the GMAT will end up answering up to 10 unscored experimental math questions and 10 unscored experimental verbal questions. These questions are interspersed with the actual, scored questions with no way to identify them as experimental.
Second, the writers at ACT have a general sense of what makes a 50th percentile question, or a 75th percentile question, or a 90th percentile question. Because each test is designed to evaluate proficiency in the same range of topics, the writers have to come up with ways to test the same concepts at different levels of difficulty. That’s where layering comes in.
So, in a nutshell, a simple problem is made increasingly complex by adding information to obscure the core issues. In Sentence Correction questions, you are given a sentence in which a portion has been underlined. Your task is to determine whether the underlined portion is correct as it stands or whether it needs to be replaced with one of the answer choices in order to make the sentence grammatical and clear.
For example, let’s consider the following sentence:
The dog are friendly.
It does not take much effort to see that this sentence is flawed: the noun (dog) is singular but the verb (are) is plural. This would be much too easy for the GMAT, so the test writers must camouflage the error. One simple way to do so is to insert a lot of unnecessary verbiage between the noun and verb. We call this verbiage the middleman. For example:
The dog, which was one of two puppies rescued from the shelter, are friendly.
The subject-verb flaw is a little harder to see now, but still fairly apparent on a first read. If we take out the middleman (the intervening clause), we are back to the original sentence (The dog are friendly). Notice, however, that the writers have inserted a plural noun (puppies) in the new clause so that you have plurality on the brain when you read are friendly. If you are already thinking in plural terms, you are much less likely to spot the error. Even on a visual level, the subject of the sentence (dog) is so far removed from the verb (are) that the eye quickly alights on puppies as a possible subject for the plural are. As tricky as this may already seem, the writers can put yet another kink in the rope:
Two puppies were rescued from the shelter, but neither of them are friendly.
The error in this sentence is significantly less apparent than those in the previous examples, though it is still the same error: subject-verb disagreement. Here the subject is neither (of them), which is singular (think of it as neither one of them). The verb, however, is still plural (are). The saga of the mismatched subject and verb goes on. Can the writers make the problem even harder to spot? Sure! Let’s take a look at the following example:
Neither of the two puppies that were rescued from the shelter are friendly.
If you compare this sentence with the previous examples, the error is almost completely camouflaged. We can see that the subject is neither (one), which is singular, but the verb are is still plural. The core is simply neither (one) are friendly. The test writers have managed to layer enough junk into the middle of the sentence to make it very difficult to spot the error. That junk, though, is just extra information about the subject: Neither (one) are friendly. Only those who really know the rules backwards and forwards are going to be able to avoid this trap.
We have gone from The dog are friendly to Neither of the two puppies that were rescued from the shelter are friendly in a few steps, obscuring the central subject-verb issue along the way. Breaking sentences down into their component parts and analyzing their relationships is the key to success in Sentence Correction.
Major Take-Aways
- When studying, try to figure out how the author layered the sentence to make it more difficult. Can you write a simpler version of the sentence (perhaps with only the core information, not everything)? How did the author make this sentence so tricky?
- If you can split out the core and understand how the different pieces of extra info fit into the core, then you won’t be as likely to fall into a trap on a layered question. (You still might fall into a trap “ but you will have a much better chance of avoiding it!)