Chang 2004.

Methods	ITS analysis Data were not analysed appropriately*
Participants	All patients on the surveillance system of a University Medical centre, Taiwan who had a total of 24,406 tooth extractions before the intervention and 28,084 tooth extractions after the intervention
Interventions	Educational programme administered between 1999 to 2001 in which residents and interns from all specialities were given a training session about cases of erroneous tooth extraction, an explanation of the recently developed clinical guidelines regarding extraction and feedback to each speciality by instructors
Outcomes	Annual incidence rates of wrong‐site tooth extraction
Notes	*Data re‐analysed
Risk of bias
Bias	Authors' judgement	Support for judgement
Intervention independent of other changes?	Unclear risk	No statement of another intervention occurring concurrently
Shape of the intervention effect pre‐specified?	Low risk	Point of analysis is point of intervention
Intervention unlikely to affect data collection?	Low risk	Unlikely to affect data collection ‐ data collection the same before and after the intervention
Knowledge of the allocated interventions adequately prevented during the study	Low risk	Objective outcomes
Incomplete outcome data (attrition bias) All outcomes	Low risk	Unlikely to have missing outcome data
Selective reporting (reporting bias)	Low risk	The pre‐specified outcomes that are of interest in the review have been reported in the pre‐specified way
Other bias	Low risk	Data re‐analysed