Table A1.

Baseline characteristics difference between attrition and no missing sample.

Variables	Pooled Sample (n = 2169)			Gansu (n = 786)			Shaanxi (n = 1383)
	Attrition Group	None Attrition Group	Difference	Attrition Group	None Attrition Group	Difference	Attrition Group	None Attrition Group	Difference
	(1)	(2)	(2) − (1)	(4)	(5)	(5) − (4)	(7)	(8)	(8) − (7)
Student:
Grade (1 = fourth)	4.644	4.6	−0.044	4.75	4.622	0.128	4.603	4.591	−0.012
	(0.481)	(0.49)	(0.057)	(0.442)	(0.485)	(0.092)	(0.493)	(0.492)	(0.069)
Male Sex (1 = Yes)	0.415	0.496	0.081	0.5	0.517	−0.017	0.379	0.484	0.105
	(0.496)	(0.500)	(0.058)	(0.511)	(0.500)	(0.092)	(0.489)	(0.500)	(0.072)
Severity of Myopia	0.514	0.512	−0.002	0.543	0.495	−0.048	0.502	0.522	0.02
	(0.255)	(0.231)	(0.028)	(0.292)	(0.249)	(0.058)	(0.24)	(0.22)	(0.031)
Not Wearing Eyeglasses at Baseline (1 = Yes)	0.854	0.847	−0.007	0.833	0.873	−0.04	0.862	0.832	−0.03
	(0.356)	(0.36)	(0.036)	(0.381)	(0.334)	(0.069)	(0.348)	(0.374)	(0.043)
Baseline standardized math score	0.071	0.260	0.189	−0.286	0.143	0.429 *	0.218	0.328	−0.189
	(1.152)	(0.987)	(0.124)	(1.187)	(0.971)	(0.216)	(0.146)	(0.027)	(0.123)
Family:
One or Both Parents with ≥12 years education (1 = Yes)	0.293	0.213	−0.08	0.333	0.235	−0.098	0.276	0.201	−0.075
	(0.458)	(0.408)	(0.048)	(0.482)	(0.423)	(0.09)	(0.451)	(0.399)	(0.057)
Family Asset Value, 10 thousand	2.926	3.083	0.157	1.793	1.487	−0.306	3.395	4.002	0.607
	(3.52)	(3.426)	(0.419)	(2.842)	(1.899)	(0.539)	(3.686)	(3.757)	(0.528)
One or Both parents out-migrated for work (1 = Yes)	0.549	0.463	−0.086	0.625	0.524	−0.101	0.517	0.428	−0.089
	(0.5)	(0.499)	(0.055)	(0.495)	(0.5)	(0.09)	(0.504)	(0.495)	(0.069)
Teacher & Schools:
Teachers Finished College or Higher Education	0.488	0.507	0.019	0.458	0.487	0.029	0.500	0.518	0.018
	(0.503)	(0.500)	(0.064)	(0.509)	(0.5)	(0.12)	(0.504)	(0.5)	(0.075)
Share of Teachers that Held Professional Titles	0.876	0.893	0.017	0.908	0.912	0.004	0.863	0.883	0.02
	(0.182)	(0.25)	(0.022)	(0.154)	(0.346)	(0.041)	(0.192)	(0.171)	(0.023)
Class Size	42.439	44.761	2.322	43.75	47.189	3.439	41.897	43.365	1.469
	(13.006)	(12.059)	(1.62)	(12.333)	(10.745)	(3.17)	(13.341)	(12.546)	(1.938)
Observations	82	2087	-	24	762	-	58	1325	-

Notes: Columns 1 to 3 show the descriptive statistics and attrition check for the whole pooled sample. Columns 4 to 6 show the descriptive statistics and attrition check for Gansu province. Columns 7 to 9 show the descriptive statistics and attrition check for Shaanxi province. Information on blackboard use was missing for 80 of the 82 attrition sample and therefore was not shown. The coefficients of difference estimated by regressing each of the baseline characteristics on the attrition dummy with standard errors clustered at the school level in parentheses. * p < 0.10.