Table 2.

Coefficients (SEs) from the structural equation model predicting number of fathered offspring surviving to 15 years as a function of the annual cohort's sex ratio at birth and control variables. Father's marital status and number of liveborn offspring were used to estimate standard errors. Sex ratio scaled as a z-score. We fitted a zero-inflated Poisson distribution given its smallest AIC and BIC value relative to that of Poisson and negative binomial distributions. Results control for clustering of sibling observations within mother.

	father's total number of children surviving to 15 years
variable	coef.	s.e.	p-value
cohort's sex ratio at birth	–0.042	(0.023)	0.08
firstborn son (ref: all others)	–0.22	(0.07)	0.003
interbirth interval (in years)	–0.04	(0.02)	0.04
socioeconomic status at birth†	0.09	(0.04)	0.02
annual cohort size	–0.06	(0.02)	0.003
region of birth (ref: mainland)
archipelago	–0.27	(0.05)	<0.001
northern region	–0.63	(0.08)	<0.001
time propensity of outcome	0.10	(0.05)	0.03
indicator variables for month of birth	included; not shown
number of observations analyzed	3503

^†1, poor; 2, middle class; 3, wealthy.