title: A note on the IQ of monozygotic twins raised apart and the order of their birth.
abstract: This note examines James Shields' sample of monozygotic twins raised apart to entertain the hypothesis that there is a significant association between the measured IQ of these twins and the order of their birth. A non-parametric test supports this hypothesis and then a linear probability function is estimated that discriminates the effects on IQ of birth order from the effects of birth weight.
mesh_terms: D001699:Biometry; D001722:Birth Order; D001724:Birth Weight; D005260:Female; D006801:Humans; D007360:Intelligence; D008297:Male; D011247:Pregnancy; D012931:Social Environment; D014427:Twins; D014430:Twins, Monozygotic