Payments for ecological restoration and internal migration in China: the sloping land conversion program in Ningxia

Table 9 The effect of SLCP program on migration with PSM method

Method (parameters)	Number of treated	Number of controls	ATT coefficient	Std. Err.
Nearest-Neighbor matching (10 neighbors; caliper value: 0.001)	3,072	1,996	0.1619^***	0.0137
Radius matching (caliper value: 0.001)	3,072	1,996	0.1602^***	0.0136
Kernel matching (Epanechnikov kernel; bandwith: 0.06)	3,166	1,996	0.1576^***	0.0115
Kernel matching (Epanechnikov kernel; bandwith: 0.03)	3,166	1,996	0.1607^***	0.0116
Kernel matching (Gaussian kernel; bandwith: 0.01)	3,166	1,996	0.1620^***	0.0115

Source: Survey data collected by Beijing Normal University and Hitotsubashi University in 2009.
Notes: Standard errors for the matching estimates are bootstrapped standard errors using 100 replicates.
The propensity score is estimated using a logit of treatment status on individual characteristics (gender, initial age, marital status, years of education, local cadre status), initial household and village characteristics (household size, number of elderly, migration network), and a number of interaction terms. A common support is imposed for each matching method by dropping 5 percent of the treatment observations at which the score density of the control observations is the lowest. ^***: significant at 1%.