Doug Rex of Indiana University — one of the most respected gastroenterologists in the world — decided to use video recording to check the thoroughness of colonoscopies being performed by doctors in his practice.
After assessing 100 procedures, he announced to his partners that he would be timing and scoring the videos of their future procedures (even though he had already been doing this). Overnight, things changed radically. The average length of the procedures increased by 50%, and the quality scores by 30%. The doctors performed better when they knew someone was checking their work.
More on the use of videotapes to measure quality of care in the WSJ.