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Guessing on the SAT May 31, 2010

Posted by Jason McDonald in : SAT tips , trackback

Not everyone should guess on the SAT. In fact, most people shouldn’t.  Decide for yourself before test day if you should guess or not.

The majority of test takers have heard there’s a “guessing penalty” on the SAT. This is a partial truth. While the computer grading system has no way of knowing which answers were guesses, it does subtract a fraction of a point for wrong answers.

Many major test prep companies encourage guessing on SAT questions if one or more answers can be ruled out. See table below for a sample of this oversimplified logic. Their logic states that statistically, in the long run, scores will increase with “educated guessing” because the points received for correct guesses are greater than the fractions lost for those missed. This logic is flawed for most guessers for three reasons:

  1. It assumes the ruled out answers are, in fact, incorrect. If test takers fall for one of the many SAT traps to determine an answer looks wrong, they’re out of luck no matter how much guessing karma they have!  Read myth #3 to see an example of how uninformed test takers can rule out the correct answer.
  2. If the guesser correctly rules out one or more answers, (s)he is likely to choose the final answer based on what looks right (This is not random guessing!) That’s right, the test writers have laid traps with answers that look right and they’ve included questions with correct answers that look wrong.
  3. Even if the guesser correctly rules out one or more answers, and randomly chooses one of the remaining answers, (s)he is not likely to do this enough on a single test for the statistics to reliably play out (ever heard of too small a sample size?). Everyone knows that landing heads on a fair toss has a probability of 50%. Does that mean it will definitely land heads 2 out of 4 times? 5 out of 10? No way! It’s not unusual to land heads (or tails) more than 7 out of 10 times. This same principle applies to your guessing on a handful of questions.  You may not have only wasted valuable time coming up with those guesses, but you may very well have lost points on the five or ten questions in which you guessed.
Potential benefit for SAT guessing on 100 questions
Rule out before guessing Likely correct answer points Likely incorrect answer points Likely net increase
0/5 20 ¼ of 80 = -20 0
1/5 25 ¼ of 75 = -18.75 6.25
2/5 33 ¼ of 66 = -16.5 16.5
3/5 50 ¼ of 50 = -12.5 37.5

NOTE — for the above table to have any significance, the following three conditions must be met:

1. Correct answer is never ruled out
2. Guessing is truly random
3. Guesses are made for a significant number of questions (the above table was based on 100 guesses! There are only 54 in the entire math section!)

MORAL OF THE STORY

If you think you can increase your SAT score through guessing, do yourself a favor. Learn how to recognize SAT traps and where they frequently occur, as well as common mistakes made in ruling out answers. Then guess randomly from the remaining choices. I suggest choosing the same letter all the time, such as (A) or if that was ruled out, then (B) or if that was ruled out, then (C), etc.

Some people benefit from guessing in the verbal section but not the math, while others gain points from guessing in the easy portion but not the medium or difficult ones. Most test takers consistently lower their score altogether from guessing!

Don’t believe the major test prep companies, your guidance counselor or even your math teacher when it comes to guessing on the SAT.  Heck, don’t even believe me and my ten years of SAT tutoring experience!  Next time you take a practice test, put a mark by questions where you guessed. Score your test with and without those guesses and you tell me, should you guess on SAT math questions?  I bet not.

Comments»

1. Paul - May 16, 2012

love your post. there is, however, a fourth reason not to guess when many companies claim you should. advocates claim ” the points received for correct guesses are greater than the fractions lost for those missed.” but that kind of expected value analysis is strictly applicable to massive amounts of data – iow, if each student were answering about 10,000 questions, it might even out for them. it also pretends that kids will be sharing their ‘profit and loss’ – that a few kids coming out ahead can justify greater numbers of kids damaging their scores. this kind of misuse of a concept like expected value is disturbing because impressionable kids will hear it and think ‘ohhhhh they MUST know what they are talking about’ without realising that the person really does not understand the parameters of the concept.

2. Jason McDonald - September 11, 2011

Thank you for your feedback, Julie! Made my day :)

3. Julie - September 9, 2011

As a long time SAT tutor, your advice is excellent. The trap answers are usually so well written that it is nearly impossible to rule them out by guessing. Every part of your argument holds water. Thank you for posting this wonderful explanation.

4. Jason McDonald - April 9, 2011

Anonymous,

MYTH #6: You should not leave any grid-in questions blank because there’s no guessing penalty on that question type

While it’s true the SAT scoring system does not subtract points for wrong answers on grid-ins, the penalty is lost time. In addition to reading through the question, coming up with a solution, writing down the answer, you must bubble in each digit and decimal point. If you’ve worked through a problem and have an answer you’re unsure of, sure, take the time to transfer it to your answer sheet. If there are just a couple minutes left and there are several questions you have not looked at, better to focus on one than take the time to fill in random guesses for all of them. Accuracy is more important than speed on multiple-choice as well as grid-in questions.

5. Anonymous - April 7, 2011

I read on the Kaplan web site that you get no points off for a wrong answer on the grid questions in the math section. Is this true? Does this mean that if you don’t know the answer, that you should always guess on the grid questions?

6. Salient - March 25, 2011

Thanks. I’ve always been to told to the opposite, but your explanation is really good.

7. thang - November 24, 2008

Yes, I most positively advocate your opinion. Guessing is never the solution for SAT.