The good ward makes more mistakes
In a hospital, researchers measured which nursing team made more errors.
The teams rated best reported the most. At first the researcher thought she had botched the measurement.
Then it turned out: they did not make more errors. They just reported them.
Amy Edmondson called this psychological safety. A team where bad news can be spoken learns. One where it cannot, does not.
Where the statistics show no errors, there are no errors. In the statistics.
Source and further reading: Amy C. Edmondson: Psychological Safety and Learning Behavior in Work Teams