Table 2.

Logistic regression results predicting likelihood of Tree City USA participation as a function of community population (log).

Region	n	Estimate	SE	z-ratio	P	Pop. at 0.5 probability^{^z}
1-New England	736	1.05	0.11	9.3	<0.0001	54,553
2-Middle Atlantic	2,617	0.90	0.07	13.6	<0.0001	96,034
3-East North Central	1,617	0.83	0.06	13.6	<0.0001	15,979
4-West North Central	810	1.14	0.10	11.5	<0.0001	9,922
5-South Atlantic	1,906	0.86	0.06	15.0	<0.0001	48,823
6-East South Central	602	1.09	0.12	8.9	<0.0001	28,405
7-West South Central	1,062	1.13	0.09	12.0	<0.0001	80,731
8-Mountain	647	0.63	0.08	8.0	<0.0001	22,177
9-Pacific	1,358	0.96	0.07	14.1	<0.0001	79,342
United States	11,355	0.83	0.02	35.6	<0.0001	46,262

↵^z The predicted population at which a community has a 0.5 probability of participating in Tree City USA.