Table 3

Internal reliability of the HSOPSC’s safety culture factors in 920 responses to a longitudinal follow-up study of operating theatre staff perceptions on hospital safety culture after a stepped wedge cluster randomised controlled trial implementation of the WHO’s Surgical Safety Checklists at Haukeland University Hospital, Bergen, Norway, 2009–2017

	Survey years
	2009	2010	2017	All
Safety culture dimensions*	Items	α	α	α	α
Overall PS in hospital	4	0.78	0.71	0.76	0.76
Frequency of events	3	0.82	0.82	0.75	0.81
Unit managers support PS	4	0.85	0.84	0.80	0.84
Continuous improvement	3	0.64	0.67	0.63	0.65
Teamwork in unit	4	0.76	0.73	0.70	0.74
Open communication	3	0.67	0.72	0.67	0.69
Error feedback	3	0.72	0.77	0.78	0.76
Non-punitive	3	0.67	0.60	0.72	0.67
Adequate staffing	4	0.59	0.67	0.63	0.63
Hospital manager support PS	3	0.80	0.76	0.81	0.79
Teamwork across units	4	0.68	0.69	0.60	0.67
Handoffs and transitions	4	0.74	0.76	0.76	0.75

*All dimensions gave average scores on the included items on a scale from 1 to 5.
α, Cronbach’s alpha; HSOPSC, Hospital Survey on Patient Safety Culture; PS, patient safety.