Table 3.

Associations between the two road measures and three indicators of social class (mother and household smoking, and mother's education)

Traffic measure	Dependent variable	Road type	OR	95% CI	P-value
Distance to road (km)	Mother's	Freeway	0.95	0.91,1.00	0.04
	smoking	Highway	0.97	0.94, 1.01	0.12
		Main road	1.01	0.83, 1.23	0.94
	Household	Freeway	0.94	0.91, 0.98	0.004
	smoking	Highway	0.99	0.96, 1.03	0.70
		Main road	1.14	0.97, 1.35	0.12
	Mother's	Freeway	0.99	0.95, 1.03	0.57
	education	Highway	1.01	0.98, 1.05	0.47
		Main road	1.10	0.92, 1.32	0.29
Number of road segments within 400 metres	Mother's smoking	Freeway	0.83	0.59, 1.17	0.29
		Highway	1.00	0.82, 1.24	0.96
		Main road	1.02	0.98, 1.06	0.31
	Household	Freeway	0.91	0.72, 1.15	0.44
	smoking	Highway	1.10	0.92, 1.31	0.29
		Main road	0.99	0.96, 1.03	0.75
	Mother's	Freeway	1.03	0.83, 1.29	0.77
	education	Highway	1.08	0.89, 1.31	0.43
		Main road	1.01	0.97, 1.05	0.53

Odds ratios are on a scale of per km for distance, and per segment for the number of roads.

OR = odds ratio, CI = confidence interval