Hitting the roof: Understanding ceiling effects

Sometimes a test can be too easy for some or all of the test takers, resulting in a large number of perfect or near-perfect scores. When this happens the test results are sometimes described as suffering from a “ceiling effect”. Although it can compromise the usefulness of a set of test results, a ceiling effect isn’t always a problem. When faced with a ceiling effect we need to think about the purpose for which the test results will be used before making a decision about the usefulness of the results and the assessment itself.