. Author manuscript; available in PMC: 2023 Oct 18.

Published in final edited form as: J R Stat Soc Ser A Stat Soc. 2021 Jul 5;184(4):1390–1413. doi: 10.1111/rssa.12716

TABLE 6.

Estimates for the effects of each of the components of the two-part model

	P(X_i > 0)		E(ln(X_i) \| X_i > 0)
	Estimate	Standard error	Estimate	Standard error
Intercept	0.3823	6.100	3.142	2.804
Gestational age at recruitment (week)	0.008	0.035	0.016	0.016
Number of prenatal visits	0.063	0.088	−0.100	0.041
Smoking during pregnancy (cigarettes/day)	0.113	0.039	0.031	0.009
Prenatal marijuana exposure (days/month)	0.336	0.220	−0.014	0.033
Prenatal cocaine exposure (days/month)	−0.074	0.094	−0.044	0.038
Prenatal opiate exposure (days/month)	−0.050	0.248	0.316	0.101
Biological mother’s education (years)	0.196	0.166	0.106	0.072
Biological mother’s verbal IQ (PPVT score)	−0.029	0.056	−0.023	0.027
Beck Depression Inventory at 6-month postpartum follow-up	−0.010	0.042	0.000	0.016
Age of a child at 7-year follow-up (years)	−0.000	0.002	−0.002	0.000
Socioeconomic status at age 7-year follow-up	0.023	0.027	0.018	0.011
Primary caregiver’s verbal IQ (PPVT score)at 7-year follow-up	0.016	0.057	0.003	0.026
HOME score at 7-year follow-up	−0.063	0.041	0.018	0.017
Beck Depression Inventory at 7-year follow-up	0.029	0.050	0.047	0.019
Number of stressful events at 7-year follow-up	0.191	0.115	0.037	0.043
Perceived life stress at 7-year follow-up	−0.020	0.024	−0.016	0.009
Biological mother’s marital status	−0.401	0.750	0.213	0.408
Primary care giver’s marital status at 7-year follow-up	−0.109	0.636	−0.273	0.303
Parity	−0.6705	0.338	0.131	0.122
Gravidity	0.3653	0.215	0.016	0.016