TY  - JOUR
AU  - Black,Sandra E.
AU  - Devereux,Paul J.
AU  - Salvanes,Kjell G.
TI  - Older and Wiser?  Birth Order and IQ of Young Men
JF  - National Bureau of Economic Research Working Paper Series
VL  - No. 13237
PY  - 2007
Y2  - July 2007
UR  - http://www.nber.org/papers/w13237
L1  - http://www.nber.org/papers/w13237.pdf
N1  - Author contact info:
Sandra Black
Department of Economics
 University of Texas
Austin, TX  78712
Tel: 512-475-8519
E-Mail: sblack@austin.utexas.edu

Paul J. Devereux
School of Economics
and Geary Institute
University College Dublin
Belfield, Dublin 4
Ireland
E-Mail: devereux@ucd.ie

Kjell Salvanes
Department of Economics
Norwegian School of Economics & Business
Hellev. 30, N-5035 Bergen, NORWAY
IZA and CEP
E-Mail: kjell.salvanes@nhh.no
AB  - While recent research finds strong evidence that birth order affects children's outcomes such as education and earnings, the evidence on the effects of birth order on IQ is decidedly mixed. This paper uses a large dataset on the population of Norway that allows us to precisely measure birth order effects on IQ using both cross-sectional and within-family methods. Importantly, irrespective of method, we find a strong and significant effect of birth order on IQ, and our results suggest that earlier born children have higher IQs. Our preferred estimates suggest differences between first-borns and second-borns of about one fifth of a standard deviation or approximately 3 IQ points. Despite these large average effects, birth order only explains about 3% of the within-family variance of IQ. When we control for birth endowments, the estimated birth order effects increase. Thus, our analysis suggests that birth order effects are not biologically determined. Also, there is no evidence that birth order effects occur because later-born children are more affected by family breakdown.
ER  -