Table 2.

Estimated Effect of Co-Payments on ED Visits per Enrollee (Poisson Model) in Copayment States

	Poisson Model
	Observed Rate Change*	95% CI**	P value
Mean Difference	0.05	−0.05 to 0.16	0.30
2007	−0.04	−0.19 to 0.11	0.56
2008	0.02	−0.08 to 0.13	0.66
2009	0.09	−0.02 to 0.20	0.11
2010	0.15	−0.00 to 0.30	0.05

^*indicate change in rates of ED visits per enrollee when compared to the pre-policy mean difference

^**CI was calculated using bootstrapping with 500 samples