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# Correction for guessing

A **guessing penalty** is a penalty imposed on a test taker’s test score for incorrectly guessing the answer to a free response multiple choice question.^{[1]}

Rather than scoring 0 for an incorrect answer, the test taker scores a negative score of the number of marks available for the answer divided by the number of answers. So, for example, if the question is worth 1 mark and there are 4 answers (1 key response and 3 distractors), then an incorrect answer scores -1/4. The test taker also has the option of not answering the question and scoring 0 marks.

The best strategy to follow is for the test taker to answer the questions they know the answers to, but leave those they don’t know the answer to.

Applying this penalty reduces the expected value of adopting a guessing strategy to 0. However, as the standard deviation is non-zero, it means it’s possible to score a negative. It also does not prevent students who adopt a guessing strategy from passing, but rather makes it less likely that they will pass.