. Author manuscript; available in PMC: 2015 Jan 22.

Published in final edited form as: J Hum Resour. 2013 Mar 1;48(4):945–968. doi: 10.3368/jhr.48.4.945

Table 5.

Treatment effects on achievement z-score by low-income status using IHDP HLBW sample with ECLS-B weights

Outcome (sample size)		Model
Outcome (sample size)		A	B	C
Age 8 reading (n=308)	Treatment	−0.116 (0.209)	−0.041 (0.261)	−0.456 (0.267)
	Low income		−0.643^*** (0.156)	−0.936^*** (0.123)
	Treatment x (low income)			0.804^*** (0.184)
Age 8 Math (n=312)	Treatment	0.120 (0.149)	0.187 (0.206)	−0.137 (0.197)
	Low income		−0.594^* (0.257)	−0.830^** (0.281)
	Treatment x (low income)			0.636^** (0.224)

Coefficient significance (within site correlation corrected standard errors):

0.10

^**

0.05

^***

0.01. All models also condition on child gender, birth weight, gestational age at birth, neonatal health index, and site indicators. Estimates in appendix.