Table 2.

Differences in the Hawthorne effect among various departments, occupations, observation times, observation locations, number of indications per hand hygiene opportunity, and hand hygiene indications

Variable	Pair no.	Hand hygiene compliance (%)		Hawthorne effect (percentage point difference)	p valuea
		Overt observation	Covert observation
Department (N = 6094)					0.255
Medicine	1212	76.6	53.3	23.3
Surgery	1258	76.1	48.5	27.6
Others	577	86.5	70.2	16.3
Occupation (N = 6094)					< 0.001
Nurse	2105	84.2	54.2	30.0
Physician	619	67.9	57.4	10.5
Caregiver	106	50.0	42.5	7.5
Others	217	64.1	57.1	7.0
Timeb (N = 6094)					1.000
Day shift	2493	78.5	55.9	22.6
Early night shift	516	77.1	50.4	26.7
Late night shift	38	73.7	28.9	44.8
Location (N = 6094)					< 0.001
Ward	2034	78.1	50.3	27.8
Intensive care unit	880	80.6	69.2	11.4
Outpatient department	133	64.7	24.1	40.6
Numbers of indications per hand hygiene opportunityc (N = 4686)					0.541
1	2301	76.7	53.2	23.5
2	42	85.7	73.8	11.9
Hand hygiene indicationd (N = 1300)					0.130
Before touching a patient	270	72.2	47.4	24.8
Before clean/aseptic procedures	19	78.9	52.6	26.3
After body fluid exposure risk	18	77.8	50.0	27.8
After touching a patient	287	83.3	59.9	23.4
After touching patient surroundings	56	55.4	53.6	1.8
Overall (N = 6094)	3047	78.2	54.6	23.6

^aGeneralized estimating equations were used to test whether there were significant differences in the Hawthorne effect among different categories of each variable

^bThe day shift was 0800–1600 h, the early night shift 1600–2400 h, and the late night shift 2400–0800 h

^cOnly the matched pairs with the same number of indications for both overt and covert observation methods were included

^dOnly the matched pairs with the same HH indication for both overt and covert observation methods were included