. Author manuscript; available in PMC: 2015 Mar 1.

Published in final edited form as: Int J Drug Policy. 2014 Jan 18;25(2):308–319. doi: 10.1016/j.drugpo.2014.01.003

Table 4.

Differences-in-Differences Estimates of Effects of Medical Marijuana Supply Provisions on Potency (THC %), 1990-2010

Variables	(1)	(2)	(3)	(4)	(5)
Legally Operating Dispensaries	0.99 (0.46)^**		0.91 (0.39)^**	1.02 (0.44)^**	0.90 (0.40)^**
De Facto Operating Dispensaries		-0.29 (0.56)		-0.41 (0.53)	-0.26 (0.47)
Home Cultivation	0.46 (0.51)	0.61 (0.59)		0.72 (0.60)
Home Supply Index			0.13 (0.17)		0.19 (0.18)
Decriminalization Policy	2.79 (1.06)^**	2.51 (1.04)^**	2.86 (1.14)^**	2.65 (1.02)^**	2.79 (1.13)^**
Log Outdoor Plots Seized per 100,000 Population (Lagged 1 Year)	-0.02 (0.18)	0.01 (0.17)	-0.02 (0.18)	-0.02 (0.18)	-0.01 (0.18)
Log Indoor Grows Seized per 100,000 Population (Lagged 1 Year)	-0.19 (0.15)	-0.26 (0.15)^*	-0.20 (0.15)	-0.19 (0.15)	-0.20 (0.15)
Constant	18.40 (57.30)	46.70 (55.45)^*	27.07 (57.64)	22.55 (59.53)	31.26 (60.64)
R²_adj	33.9%	33.9%	33.9%	33.9%	33.9%

Note: Cluster robust standard errors are reported in parentheses. All models include state and year fixed effects and control variables. N = 39,157.

Significance levels:

10%,

^**

5%,

^***