Table 4

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

Outcome (sample size) Model
ABC
Age 1 IQ (n=330)Treatment0.109
(0.132)		0.112
(0.133)		0.065
(0.177)
 Low income−0.037
(0.122)		−0.072
(0.171)
 Treatment × (low income)0.097
(0.253)
Age 2 IQ (n=322)Treatment0.793***
(0.160)		0.878***
(0.223)		0.433*
(0.219)
 Low income−0.875***
(0.244)		−1.181***
(0.270)
 Treatment × (low income)0.872**
(0.280)
Age 3 IQ (n=328)Treatment0.903***
(0.147)		1.001***
(0.181)		0.323
(0.210)
 Low income−1.017***
(0.192)		−1.482***
(0.240)
 Treatment × (low income)1.319***
(0.308)
Age 5 IQ (n=295)Treatment0.102
(0.116)		0.148
(0.166)		−0.264
(0.201)
 Low income−0.509*
(0.246)		−0.820***
(0.231)
 Treatment × (low income)0.861***
(0.201)
Age 8 IQ (n=311)Treatment0.156
(0.158)		0.224
(0.169)		−0.067
(0.323)
 Low income−0.595**
(0.185)		−0.806***
(0.196)
 Treatment × (low income)0.572
(0.361)

  • 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.