Table 3.

General linear model for repeated measures examining patients with neck pain-related disability who presented at a neck and back outpatient clinic and completed a questionnaire for the initial assessment (Time 1) and six months later (Time 2) (N = 1767). Higher scores indicate greater neck pain-related disability

Time 1			Time 2
Model	M	SD	M	SD	M diff	SE diff	p diff	F	df	df(error)	p
Mean values of neck pain-related disability
No sickness absence	14.73	6.55	13.97	7.41	-0.76	0.22	< 0.001
Graded sickness absence	18.18	6.21	16.46	7.32	-1.71	0.30	< 0.001
Full sickness absence	21.12	7.86	18.75	9.19	-2.37	0.29	< 0.001
Between subjects
Intercept								10854.84	1	1764	< 0.001
Sickness absence								110.99	2	1764	< 0.001
Within subjects
Time								106.27	1	1764	< 0.001
Time * sickness absence								10.50	2	1764	< 0.001