The distribution of opportunities for three types of observers to assess hand hygiene program during a one-year study conducted during 2010 and 2011 by the Center of Excellence for Hand Hygiene (HH) at the National Taiwan University Hospital.

*The differences among the observers in frequency of opportunities to witness HH performances were significant; P<0.001.
†The differences among the observers in proportion of observations according to professional categories, department or HH indications were significant; P<0.001.