Guess where: The position of correct answers in multiple-choice test items as a psychometric variable

In this article, the authors show that test makers and test takers have a strong and systematic tendency for hiding correct answers - or, respectively, for seeking them - in middle positions. In single, isolated questions, both prefer middle positions to extreme ones in a ratio of up to 3 or 4 to 1. Because test makers routinely, deliberately, and excessively balance the answer key of operational tests, middle bias almost, though not quite, disappears in those keys. Examinees taking real tests also produce answer sequences that are more balanced than their single question tendencies but less balanced than the correct key. In a typical four-choice test, about 55% of erroneous answers are in the two central positions. The authors show that this bias is large enough to have real psychometric consequences, as questions with middle correct answers are easier and less discriminating than questions with extreme correct answers, a fact of which some implications are explored.