Guessing on the SAT
A common misconception about the SAT is that it's bad to guess. We hope that after you read this article you'll think otherwise.
Omitted Answer Equals Zero
First of all, many students believe that because there is "no penalty" for an omitted question (i.e. leave question blank), then you should always omit rather than guess. Wrong! The problem with this thinking is that if you omit a question you are getting ZERO points for that question. To cover the other possibilities: you get one point for a correct answer and -1/4 point for an incorrect answer. By the end of the SAT, you want to have racked up as many points as possible.
When to Guess on the SAT
So now you're thinking, "I get NEGATIVE points if I guess incorrectly and zero points if I just omit. Isn't it better to omit??" If you cannot eliminate any answer choices then yes, you should omit; however if you can eliminate just one answer then you should guess.
Benefit of Guessing on the SAT
Assume you've eliminated one wrong answer choice. That leaves you with four answer choices to guess from. If you randomly guess from the four remaining answer choices, then you have a probability of 1/4 of guessing correctly. Therefore the expected point value for your guessed question is
Expected points when you guess after eliminating one wrong answer choice
= (Probability correct X Point value for correct) + (Probability incorrect X Point value for incorrect)
= (1/4) X (1) + (3/4) X (-1/4) = 1/16 = .0625
The main thing to notice is that the expected value is positive! Hence, if you can eliminate at least one wrong answer choice, it's more likely that you will get positive points rather than negative points. The more wrong answer choices that you can eliminate, the better your results will be.
If you can't eliminate any wrong answer choices, omit the question. If you can eliminate one or more wrong answer choices, GUESS!