The concept of knowledge and how to measure it

Knowledge is often defined as a belief that is true and justified. This definition has led to its measurement by methods that rely solely on the correctness of answers. A correct or incorrect answer is interpreted to mean simply that a person knows or does not know something. Such methods of measurement have serious deficiencies that can be alleviated by expanding the definition of knowledge to include the test‐taker's certainty. The person's certainty about the answers on a test captures important, but now neglected, dimensions of knowledge. Historical roots of certainty as an essential component of knowledge, and some practical benefits of including it, are discussed. An epistemetric method is described which allows people to indicate “How sure are you?” about the correctness of each of their answers. A computer analysis of the person's answers and self‐assessment certainty responses provides multidimensional scores about a person's knowledge that remedy some deficiencies of knowledge assessment and achievement tests now employed.