Assessing movement control in children with mental retardation: a generalizability analysis of observers.

A generalizability study was conducted to determine the percentage of variance associated with observers and trials when assessing movement control in children with mild mental retardation. One group of observers received competency-based training and another group experienced informal training. A series of decision studies employing the variance component estimates indicated that different conditions of observation need to be employed based on the type of training received in movement control analysis. Observers receiving informal training needed to observe twice as many trials of the kick, jump, and overband throw compared to competency-trained observers to reach an acceptable level of reliability.