Table 1

Analysis of intervention effects on environmental tobacco smoke (ETS) exposure measures using generalised estimating equations (GEE) methods

Exposure measure	Mean or %				GEE estimate
Exposure measure	Baseline (n = 143)	Post-intervention (n = 133)	3 month follow up (n = 132)	12 month follow up (n = 127)	Time	Group	Interaction
p⩽0.05; *p⩽0.001; †0.005<p<0.10
NA, “confirmed reducers” not applicable at baseline.
Hair nicotine (log ng/mg)
Intervention	0.25	0.17	0.28	0.23
Control	0.23	0.19	0.32	0.23	0.002	−0.002	−0.001
Hair cotinine (log ng/mg)
Intervention	0.05	0.03	0.04	0.02
Control	0.05	0.03	0.04	0.04	−0.001*	0.003	−0.001
Parent reports (log number of cigs in past month)
Intervention	1.75	1.42	1.27	1.06
Control	1.85	1.62	1.44	1.27	−0.048**	−0.118	0.008
% confirmed reducers
Intervention	NA	46	52	61
Control	NA	45	46	56	0.015†	0.027	0.001