Table 1. Generalized linear model of sex, voluntary work, marital status, education, and income on offspring number on the basis of a Poisson error structure.

Coefficients	Estimate	Std. Error	Z value	P
Intercept	1.1481	0.023	50.163	<0.001
Income	−0.0001	0.0002	−0.438	0.661
Voluntary work (reference: yes)	−0.0855	0.0267	−3.196	0.001
Education (reference: 1) 2	−0.0919	0.0248	−3.710	<0.001
3	−0.1373	0.0278	−4.937	<0.001
4	−0.2163	0.0293	−7.383	<0.001
Marital status (reference: 1) 2	−0.2093	0.2889	−0.725	0.469
3	−0.0874	0.0294	−2.970	0.003
4	−0.0052	0.0330	−0.158	0.874
5	−4.335	0.3777	−11.478	<0.001
Sex (reference: male)	0.0228	0.0249	0.913	0.361
Voluntary work:sex	0.0809	0.0356	2.274	0.023

Residual deviance: 3475.1 on 4711 df;

Education: 1 = less than one year of college, 2 = 1 to 3 year college, 3 = bachelor degree, 4 = master degree and higher; Marital status: 1 = currently married, 2 = separated, 3 = divorced, 4 = widowed, 5 = never married.