Table 3.

Model R-Square change

	N	R-Square Value Demographics Only	Add CPD	p	Add Cotinine	p	Add Brand Features	p
Cotinine	2558	0.07	0.20	<.001	xxx	xxx	0.20	0.052
NNAL	2412	0.19	0.30	<.001	0.48	<.001	0.50	<.001
1-HP	220	0.17	0.23	0.001	0.35	<.001	0.43	<.001
2-HN	220	0.15	0.25	<.001	0.45	<.001	0.50	0.007
sum HF	220	0.19	0.29	<.001	0.54	<.001	0.59	0.007
sum HPH	220	0.20	0.23	0.030	0.39	<.001	0.46	0.001
As	833	0.10	0.10	0.407	0.10	0.028	0.12	0.330
Cd	837	0.46	0.48	<.001	0.49	<.001	0.51	<.001
Co	837	0.17	0.17	0.853	0.17	0.113	0.18	0.703
Pb	837	0.15	0.15	0.134	0.16	0.021	0.17	0.725
Hg	838	0.09	0.10	0.003	0.11	0.009	0.13	0.029

Note: P-Values from F-test comparing difference in R-square from consecutive models. CPD = cigarettes smoked per day.