Table 2.

Parameter Estimates from the GEE Model of Alcohol and Other Drug Outcomes

Variable	IRR	SE	z	P
Reduced Model
Centered linear time	.01	.01	−3.94	<.001
Centered quadratic time	3.83	1.40	3.68	<.001
Mindfulness hours	.47	.13	−2.82	.005
Full Model
Linear time	.01	.01	−3.76	<.001
Quadratic time	3.42	1.13	3.72	<.001
Mindfulness hours	.30	.10	−3.74	<.001
Linear time x Mindfulness hours	.90	.68	−.14	.89
Quadratic time x Mindfulness hours	.84	.20	−.74	.46

Notes. IRR = incident rate ratio. SE = Semi-robust standard error. z = z-score for the parameter.