How good is my test?

Instructors must appraise the quality of their examinations, laboratory ratings, and any other test data upon which grade decisions are made. The basic concepts of test theory are reviewed to provide some support for making these appraisals. Four types of validity are discussed. The concept of reliability is presented along with a summary of various reliability coefficients and limitations on the interpretation of reliability. Practical suggestions are offered for instructors seeking to gauge the quality of their tests. The use of the standard error of measurement for estimating the likelihood of misgrading a student is demonstrated.