Floor effect

Floor effect occurs when responses on a measure, questionnaire or scale cluster at the more negative health state end of the scale.

For instance, if the scale were administered a second time, there would be no room to detect any possible deterioration in health, even if it had occurred.

Ceiling effect

Ceiling effect occurs when responses on a measure or questionnaire cluster at the more positive health state end of the scale.

This means that if the scale were administered a second time, there would be no room to detect any possible improvements in health, even if they had occurred.