The ceiling effect is said to occur when participants’ scores cluster toward the high end (or best possible score) of the measure/instrument. The opposite is the floor effect.
In some fields (biology, physiology, etc.), the ceiling effect refers to the point at which an independent variable no longer has an effect on a dependent variable, when a kind of saturation has been reached (e.g., the phenomenon in which a drug reaches its maximum effect, so that increasing the drug dosage does not increase its effectiveness) (Baker, 2004).
In statistics/psychometrics, the term ceiling effect is used to describe how subjects in a study have scores that are at or near the possible upper limit (Everitt, 2002), so that variance is not measured or estimated above a certain level (Cramer & Howitt, 2005). In the sphere of quality of life, this limit is usually not defined by the highest score, but by the highest degree of achievement of the measured concept. Therefore, the...
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