Table 4.

Ordinary least squares (OLS) and two-stage least squares (2SLS) estimates of the effect of family size on adolescents’ completed years of education using twins as IV, adolescents ages 12–18: Brazil, 1977 to 2007

		2SLS
Sample/Instrument	OLS (1)	First Stage (2)	Second Stage (3)
Non-twin First-Born Children in Families With 2+ Children
Instrument: Twins at second birth		0.611** (0.034)
Number of siblings	−0.248** (0.003)		0.064 (0.076)
N = 227,601
Non-twin First- and Second-Born Children in Families With 3+ Children
Instrument: Twins at third birth		0.773** (0.030)
Number of siblings	−0.240** (0.003)		0.131* (0.055)
N = 269,405

Notes: Robust standard errors, shown in parentheses, allow for correlation of errors within family. All regressions include controls for age, age squared, mother’s education, father’s education, mother’s age, sex, urban location, and log of family income.

Sources: 1977–2007 PNAD data. IBGE (National Household Sample Survey).

^*p < .05

^**p < .01