Table 5.

Mean difference in percentage of crown cover between council and state forests matched by propensity score (entire sample)

Matching method	Broad-leaved	Pine
Nearest neighbor	1.8 (3.0) 75%	14.6 (4.7) 75%
Radius = 0.01	0.5 (2.7) 79%	12.0 (4.0) 74%
Kernel	1.1 (2.2) 75%	9.2 (3.5) 75%
Treated observations	355	318
All observations	582	504

Percentages refer to the percentage of treated observations (state forest polygons) used in the calculation of the mean difference. Figures in parentheses are standard errors estimated from 1,000 bootstrap replications. In broad-leaved forests, the variables used in the estimation of the propensity score functions were the first 3 powers of population density, the neighboring forest stock, broad-leaved aspect, and time to the nearest road. In pine forests, the square of the time to the nearest road was used in addition. The number of treated observations and the percentage of treated observations refer only to the point estimates because the propensity score function is reestimated in each bootstrap sample, and, accordingly, the region of common support changes.