. Author manuscript; available in PMC: 2011 Mar 1.

Published in final edited form as: J Expo Sci Environ Epidemiol. 2009 Dec 30;21(2):123–132. doi: 10.1038/jes.2009.68

Table 3.

Pearson correlation coefficients between the total logged house-dust PAH concentrations and covariates of interest.

Variable	r_p, After multiple imputation	Number imputed	r_p, Complete data	N with complete data
Residence age (years)	0.26	70	0.28	431
ln(Traffic density, veh-mi/mi²/day)^a	0.21	156	0.23	352
ln(Outdoor PAH estimate, ng/m³)	0.20	82	0.20	411
Duration at residence before enrollment (years)	0.11	55	0.12	437
Size of sampling area (m²)	0.09	0	0.09	334
Mother’s education^b	0.08	0	0.09	489
Vacuum frequency^b	−0.07	13	−0.06	480
Child’s age at enrollment (years)	0.07	0	0.09	489
Household annual income^b	0.04	19	−0.04	489
Mother’s age (years)	0.02	0	−0.04	489
Household cigarette consumption (cig/day)	−0.02	1	0.03	488

PAH, polycyclic aromatic hydrocarbons.

Traffic density was defined as the annual average daily traffic count within a 500-m radius of each residence, multiplied by the length of the road for all roads within the buffer, divided by the buffer’s area.

Categorical variable.