Table 3.

Tobit Hierarchal Regression Models of Sleep and Mechanical Pain Outcomes^a

		Temporal Summation at Knee			Pain Threshold at Knee Lateral Joint Line			Pain Threshold at Knee Medial Joint Line
Variable		Estimate	t	Pseudo-R²	Estimate	t	Pseudo-R²	Estimate	t	Pseudo-R²
Model 1				0.16			0.27			0.30
	Age	0.19	0.76		−2.01	−1.06		0.36	0.19
	Sex	−10.9^*	−3.24		140.12^*	5.11		146.62^*	5.51
Ethnicity/Race		8.86^*	2.30		−53.92^‡	−1.71		−43.58	−1.43
Education		2.03	1.34		15.76	1.26		−8.49	−0.70
	CES-D	0.32	1.50		−2.85	−1.67		−3.30^*	−2.01
	WOMAC	0.16	1.62		−0.38	−0.49		−1.27^‡	−1.72
	BMI	−0.14	−0.60		−4.08	−2.12		−2.89	−1.57
Model 2				0.16			0.28			0.32
	SHPS-A	−0.22	−0.65		0.28	0.11		1.96	0.77
Model 3				0.18			0.29			0.32
	ISI	0.52	1.51		−3.43	−1.28		−3.38	−1.30
Model 4a				0.18			0.35			0.39
Ethnicity × SHPS-A		−0.23	−0.32		−4.52	−0.85		−5.26	−1.03
Ethnicity × ISI		0.17	0.25		17.13^*	3.33		17.73^*	3.63
Model 4b				0.22			0.29			0.33
Sex × SHPS-A		0.57	0.83		−1.79	−0.32		0.94	0.18
Sex × ISI		−1.56^*	−2.50		4.02	0.83		0.91	0.19

p < 0.05

^‡

p < 0.1

Variables in Models 2-4 are centered.

BMI = body mass index; CES-D = Center for Epidemiologic Studies - Depression Scale; Eth = Ethnicity/Race; SHPS-A = Sleep Hygiene & Practices Scale, arousal-associated behaviors subscale; WOMAC = Western Ontario and McMasters Universities Arthritis Index