Table 4. Bivariate associations between each of the socio-demographic variables, occupational biomechanical factors, occupational psychosocial factors, and each of the dependent variables (neck pain intensity, neck disability and sick leave).

Variable; n = 201	Neck pain intensity	Neck disability	Sick leave
Socio-demographic characteristics
r s (P-value)
Age (years)	0.15(0.02)	0.01(0.89)	0.03(0.64)
U (P-value)
Sex	973.50(0.40)	0717.50(0.30)	930.00(0.38)
H (p-value)
Educational status	-0.14(0.04)	3.52(0.74)	-0.00(0.55)
Occupational biomechanical factors
Head load carriage history
Weight of Load (kilogram)	0.29(0.00)	0.33(0.00)	0.05(0.41)
Frequency of load Carriage (number of days per week)	0.20(0.00)	0.15(0.03)	-0.06(0.35)
Duration of load carriage (number of hours per day)	0.02(0.73)	0.16 (0.03)	0.06(0.41)
Neck posture history
Frequency of neck posture (number of days per week)	-0.20(0.00)	0.09(0.17)	-0.11(0.06)
Duration of neck posture (number of hours per day)	-0.04(0.57)	0.06(0.34)	-0.02(0.97)
Neck forward posture	-0.17 (0.02)	-0.16 (0.02)	-0.05 (0.46)
Neck backward posture	-0.15 (0.04)	-0.14 (0.05)	-0.05 (0.50)
Neck twisted (rotated) posture	0.21(0.00)	0.20(0.00)	0.06(0.35)
H (p-value)
Predominant neck posture	11.82 (0.00)	4.82 (0.01)	0.52 (0.59)
Occupational psychosocial factors
U (p-value)
Can you usually take breaks in your job in addition to the scheduled breaks?	991.00 (0.00)	2567.50 (0.82)	2401.500 (0.41)
Do you often find that you cannot work because of unexpected events, such as machine break down or material not delivered?	99.50 (0.00)	350.50 (0.01)	615.500 (0.31)
Can you usually control the order and the pace of your tasks?	1831. 50 (0.00)	2666.50 (0.00)	3278.00 (0.24)
Is the order and pace of your tasks usually dependent on others (machines, computers, customers)?	1156.50 (0.00)	2802.00 (0.00)	3634.500 (0.40)
Do you usually work under time pressure and deadlines?	2348.50 (0.00)	2534.50 (0.00)	3571.500 (0.20)

r_s = Spearman’s correlation; U: Mann-Whitney U test; H: Kruskall Wallis test