Table 1. Neck pain characteristics reported as mean ± standard deviation for each group.

	Pain Controls	Manipulation	Healthy	Pain vs. Healthy†	Pain Control vs. Manipulation†
Frequency of neck pain (days per month)	16.9 ± 9.1	14.5 ± 8.8	1.0 ± 1.0	<0.001	0.5
Duration of neck pain (years)	1.9 ± 1.5	3.2 ± 2.2	**	**	0.09
Most severe pain intensity in previous 6 mo (10 cm VAS)	5.6 ± 2.1	6.4 ± 2.1	1.4 ± 1.6	<0.001	0.4
Chronic Pain Grade Scale	1.5 ± 0.7	1.7 ± 0.6	**	**	0.3
Disability Days (average in previous 6 mo)	2.2 ± 3.3	5.4 ± 8.2	**	**	0.2

^†values reported as P values from independent sample t tests

** not applicable

VAS, visual analog scale presented as a continuous line