Context
The average daily census on the study unit was 14.6
patients. The registered nurse (RN)-to-patient ratio
was around 1 : 4 or 1 : 5 on the day shift, 1 : 5 to
1 : 7 on the evening shift and 1 : 7 to 1 : 10 on the
nightshift. The RN-to-nursing aide ratio was 8 : 2.
We could not use these descriptions of nursing context
as control variables in the analyses because the database
was not available to retrieve daily variations in
nursing context. It was not possible to look at data
based on individual nurses working in this unit; however,
information on individual surgeons was available
and used as a contextual variable.