Table 2.

Building multiple regression models of variation in annual management cost and benefit-to-cost ratio of field conservation projects

Dependent variable	Intercept	Independent variables (coefficient, t)			Overall r2
		GNP per unit area, $ km−2 y−1	PPP	Project area, km2
Cost, $ km−2 y−1	1.61**	0.57, 8.13**	−0.70, 2.34*	−0.46, −9.12**	0.81**
Ratio of number of threatened bird species per 1/4° grid to cost, $ km−2 y−1†	0.35, NS	−0.45, 4.74**	3.84, 8.50**	0.22, 2.46**	0.76**

n = 139 throughout. All variables log₁₀-transformed except: †, log₁₀ (ratio of number of threatened bird species per 1/4° grid to cost) + 0.001-transformed. 

^*, P < 0.05; 

^**, P < 0.01; 

^**, P < 0.001; NS, not significant.