The term ceiling effect is a measurement limitation that occurs when the highest possible score or close to the highest score on a test or measurement instrument is reached, thereby decreasing the likelihood that the testing instrument has accurately measured the intended domain. A ceiling effect can occur with questionnaires, standardized tests, or other measurements used in research studies. A person's reaching the ceiling or scoring positively on all or nearly all the items on a measurement instrument leaves few items to indicate whether the person's true level of functioning has been accurately measured. Therefore, whether a large percentage of individuals reach the ceiling on an instrument or whether an individual scores very high on an instrument, the researcher or interpreter has to consider that ...