Table 3

Summary Statistics of Explanatory Variables

Variable	Measurement Unit	N	Mean	Std. Dev.	Min.	Max.
10-km-cell level
Land quality	1,000 kg/ha	68,918	1.728	2.807	0.000	14.168
Terrain slope	degrees	68,918	3.091	4.154	0.000	66.250
Elevation	km	68,918	1.333	1.342	-0.153	6.444
Precipitation, 1991–1995	1,000 mm	68,918	0.540	0.442	0.007	1.877
Precipitation, 1996–2000	1,000 mm	68,918	0.547	0.461	0.006	1.824
Precipitation, 2001–2005	1,000 mm	68,918	0.681	0.527	0.002	2.865
Standard deviation of precipitation, 1991–1995	1,000 mm	68,918	0.091	0.082	0.002	0.402
Standard deviation of precipitation, 1996–2000	1,000 mm	68,918	0.092	0.070	0.002	0.368
Standard deviation of precipitation, 2001–2005	1,000 mm	68,918	0.092	0.080	0.004	0.788
Temperature, 1991–1995	°C	68,918	8.027	7.470	-16.440	24.820
Temperature, 1996–2000	°C	68,918	8.412	7.498	-15.780	25.040
Temperature, 2001–2005	°C	68,918	9.225	6.826	-4.696	26.295
Standard deviation of temperature, 1991–1995	°C	68,918	0.383	0.095	0.084	0.820
Standard deviation of temperature, 1996–2000	°C	68,918	0.561	0.120	0.239	1.144
Standard deviation of temperature, 2001–2005	°C	68,918	0.252	0.127	0.004	2.576
County level
Per hectare urban GDP, 1989	million ¥/ha	2,034	0.056	0.149	0.001	4.387
Per hectare urban GDP, 1996	million ¥/ha	2,034	0.123	0.298	0.001	8.681
Per hectare urban GDP, 2000	million ¥/ha	2,034	0.186	0.381	0.003	6.853
Per hectare agricultural GDP, 1989	million ¥/ha	2,034	0.012	0.119	0.000	5.325
Per hectare agricultural GDP, 1996	million ¥/ha	2,034	0.015	0.034	0.000	0.659
Per hectare agricultural GDP, 2000	million ¥/ha	2,034	0.018	0.043	0.000	0.977
Per capita urban GDP, 1989	¥10,000	2,034	0.887	0.696	0.050	6.090
Per capita urban GDP, 1996	¥10,000	2,034	1.531	1.333	0.024	13.377
Per capita urban GDP, 2000	¥10,000	2,034	2.216	1.906	0.041	19.606
Per capita rural GDP, 1989	¥10,000	2,034	0.115	0.194	0.004	6.379
Per capita rural GDP, 1996	¥10,000	2,034	0.156	0.120	0.010	1.722
Per capita rural GDP, 2000	¥10,000	2,034	0.187	0.146	0.007	2.378
Road density, 1988	miles/ha	2,034	0.751	1.656	0.000	41.877
Road density, 1995	miles/ha	2,034	0.866	1.794	0.000	42.901
Road density, 2000	miles/ha	2,034	1.043	2.136	0.000	47.960
Agricultural investment, 1994	million CNY	2,034	0.075	0.387	0.000	11.783
Agricultural investment, 1995–1999	million ¥	2,034	0.076	0.417	0.000	13.354
Agricultural investment, 2000	million ¥	2,034	0.095	0.527	0.000	17.057