Would you expect to see a floor or ceiling effect if you were interested in assessing the ability of healthy, 20 year olds to balance on one foot and the time balancing on one foot was your dependent measure and there was a 1 minute time limit on the balance test?
It might be expected that a healthy 20-year-old could balance on one foot well beyond 1 minute. Cutting off the test at 1 minute might not give the data you're really interested in.
