TO GUESS OR NOT TO GUESS - A DECISION-THEORETIC VIEW OF FORMULA SCORING

Multiple-choice tests are often scored by formulas under which the res pondent's expected score for an item is the same whether he or she omi ts it or guesses at random. Typically, these formulas are accompanied by instructions that discourage guessing. In this article, we look at test taking from the normative and descriptive perspectives of judgmen t and decision theory. We show that for a rational test taker, whose g oal is the maximization of expected score, answering is either superio r or equivalent to omitting-a fact which follows from the scoring form ula. For test takers who are not fully rational, or have goals other t han the maximization of expected score, it is very hard to give adequa te formula scoring instructions, and even the recommendation to answer under partial knowledge is problematic (though generally beneficial). Our analysis derives from a critical look at standard assumptions abo ut the epistemic states, response strategies, and strategic motivation s of test takers. In conclusion, we endorse the number-right scoring r ule, which discourages omissions and is robust against variability in respondent motivations, limitations in judgments of uncertainty, and i tem vagaries.