How do I develop a psychological test or questionnaire?

The purpose of this How-to article is to provide physicians and other health professionals working in the field of medical education research with a basic understanding of the construction of tests or questionnaire measures. The construction of such measures is too complex to be described on a few pages. Therefore, this article can only enable readers to roughly evaluate such measures or to convey an idea of how these are generally constructed. The article outlines various phases of test or questionnaire construction. It begins with the content phase, in which a construct is defined, if possible, by drawing on theories and models. Here, items are written, a response format is selected, the instruction is formulated, and pilot tests are conducted. In the structural phase, the structure of the test or questionnaire is evaluated using suitable test statistical methods and statistical parameters. In the final phase (external phase), additional evidence for the validity of test or questionnaire results is sought. The validation of such measures is not the last step in the construction of tests or questionnaires as it is to be considered in all phases of test or questionnaire construction. The validation of test and questionnaire measures is theoretically and methodically demanding and should never be considered complete. Strictly speaking, it should not be said that a test or questionnaire is valid, because validity is not a property of such measures. It rather is statements and conclusions based on test or questionnaire results that can be valid.