# The Key to GMAT Critical Reasoning: Reading to find the missing link Part 3

There are a variety of different ways that knowing these missing links might help you find the correct answer on the GMAT.  How you use this knowledge depends on the question type.  Let’s take a look based on our example from the previous post:

At Bryowan University a group of college students participated in a sleep study. Half of them slept a full 8 hours a night for a week, the other half slept for a total of 8 hours, but were woken up two to three times during the night each night, during that week. The half that slept the full 8 hours straight performed better, on average, on a logical reasoning exam than the half whose sleep was interrupted.   Therefore, people have the best brain function when they sleep for a full 8 hours, uninterrupted.

###### Assumption

In finding these missing links, we’ve already identified several assumptions. For example, we know the author must be assuming that better performance a logical reasoning exam is indicative of better brain function.   But, as discussed earlier, knowing these missing links can help you on more than just assumption questions.

###### Weaken

If the question asks you for information to weaken the argument, the correct answer is most likely something that exploits one of those missing links. For example, if another study showed that college students who slept for 9 hours uninterrupted performed better on the logical reasoning exam than the students who slept for 8 hours uninterrupted, that would weaken the argument.

###### Strengthen

The correct answer for a strengthen question is often something that fills in the holes left by the missing links. Think about this possible answer choice: if a person has a higher performance on a logical reasoning exam, that means that there is a higher brain function in that person. This would strengthen the argument, because it strengthens the connection between the performance on the test and brain function.

###### Evaluate or Flaw

The correct answer to an Evaluate or Flaw question will likely point out one of the missing links. One example for this prompt would be: The author fails to recognize that the connection between sleep and brain function in college students is not necessarily indicative of that of the population as a whole.

###### In Summary

On the actual GMAT, a passage might not have as many missing links as this one, there may only be one or maybe none, depending on the question type. However, it is essential to look for these missing links when going through critical reasoning passages by looking for differences, however small, between the premises and the conclusion. The more you practice it, the more natural it will become. This skill also carries into reading comprehension. For example, if you are able to spot the missing links, you can more easily eliminate wrong answers for inference questions.

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I was always just an average student, but with the right course prep I was able to score a 770 on my first try. I had to wade through a lot of material to find what was right for me, but luckily for you I've done all the research for you! See more on my GMAT courses page.