Table 2.

Linear regression analysis of the predictors of the nicotine metabolite ratio (NMR) in the total sample (N=1672)

	Nicotine Metabolite Ratio (NMR) R2 = 0.076a; P <0.001
Predictor	B	Standard Error	β	P value	% Variationb
Ethnicityc	0.071	0.011	0.162	<0.001	2.3
Genderd,e	0.057	0.010	0.136	<0.001	1.7
Birth control pill use	0.036	0.050	0.017	0.47	0.03
Hormone replacement therapy use	0.114	0.054	0.050	0.036	0.24
Body mass index	−0.003	0.001	−0.108	<0.001	1.1
Alcohol use (# drinks/week)	0.003	0.001	0.070	0.004	0.46
Cigarettes per day	0.002	0.001	0.062	0.012	0.36

^aTogether the predictors account for 7.6% of the variation in NMR

^bCalculated by squaring the part correlation coefficient (not shown), and multiplying by 100

^cAfrican Americans and Caucasians were coded as ‘0’ and ‘1’, respectively, in the model

^dMales and females were coded as ‘0’ and ‘1’, respectively, in the model

^eWhen we restricted the model to females only (N=756), to further examine the effect of birth control pill and hormone replacement therapy use, the predictors (gender is excluded) together explained 6.6% of the variation in NMR. The standardized beta values for birth control pill and hormone replacement therapy use were 0.025 (P=0.48) and 0.069 (P=0.052), respectively, in the female-only group. They uniquely contributed 0.06% and 0.48% of the variation in NMR, respectively, in females.