CATs and the importance of vocabulary

The Computer Adaptive format of the GRE makes knowing this vocabulary even more critical. On a Computer Adaptive Test (CAT), the computer tries to determine your "scoring level" by asking you a series of questions. At the beginning of the test, the computer doesn't know anything about your scoring level, so it makes broad guesses. The first question will be of average difficulty, and if you get it right, the next question will be significantly more difficult. Similarly, if you get the first question wrong, the next one will be significangly easier. If you continue to answer questions correctly, your score keeps going up. The closer the computer gets to determining your final score (ie, the closer you get to the end of the section), the smaller the adjustment it makes as it recalculates your score based on your response to each question. The most important consquence of this structure is that questions at the beginning of the section have a greater impact on your score than do those toward the end of the section. Answering questions correctly at the beginning of the section can move your score up by about 40 to 80 points. By the end of the section, each question will only adjust your score by 10 or 20 points.

The bottom line is: It is crucial that you be able to correctly answer the first several questions on the section. As we've discussed, knowing the stem words in those questions and answer choices is the key to doing so. After all, an antonym that appears in the first ten questions for which you don't know the stem word is a question you can't do much with. An antonym for which you know the stem word and at least four of the five words in the answer choices is a piece of cake.