. Author manuscript; available in PMC: 2014 Sep 1.

Published in final edited form as: Curr Atheroscler Rep. 2013 Sep;15(9):10.1007/s11883-013-0353-5. doi: 10.1007/s11883-013-0353-5

Table 1.

Calibration equation coefficients (β), standard errors (SE), and percent of biomarker variation explained (R²) from regression of log(biomarker) on log(self-report), body mass index, age, and ethnicity in the Women’s Health Initiative Nutrition and Physical Activity Assessment Study among 450 postmenopausal women. Adapted from [5]. Log-energy (kcal/day) is centered by 7.27; log-protein (grams/day) is centered by 4.14; log-protein density (g/kcal) is centered by 2.85; BMI is centered by 28.2 kg/m²; and age is centered by 70.9 years, in these analyses.

	Food Frequency				4DFR				24HRs(3)
Variable	β	SE	R²	Adj R²	β	SE	R²	Adj R²	β	SE	R²	Adj R²
Energy (kilocalories)
Intercept	7.614^*	0.009			7.597^*	0.009			7.607^*	0.009
FFQ	0.054^*	0.017	3.8	6.5
4DFR					0.161^*	0.028	7.8	13.3
24HR									0.101^*	0.026	2.8	4.8
BMI	0.013^*	0.001	26.9	45.9	0.013^*	0.001	27.0	46.0	0.013^*	0.001	28.7	48.9
Age	−0.010^*	0.001	9.7	16.5	−0.009^*	0.001	8.4	14.3	−0.009^*	0.001	9.1	15.5
Black	−0.023	0.019			−0.024	0.018			−0.024	0.018
Hispanic	−0.062^*	0.021	1.3	2.2	−0.065^*	0.020	1.5	2.6	−0.063^*	0.020	1.5	2.6
Other minority	−0.041	0.040			−0.039	0.038			−0.038	0.039
(Total)^†			41.7	71.1			44.7	76.2			42.1	71.8

Protein (grams)
Intercept	4.263	0.017			4.235	0.016			4.269	0.016
FFQ	0.135^*	0.021	8.4	16.4
4DFR					0.465^*	0.045	22.6	44.2
24HR									0.404^*	0.046	16.2	31.7
BMI	0.012^*	0.002	5.8	11.4	0.012^*	0.002	5.1	10.0	0.012^*	0.002	5.8	11.4
Age	−0.012^*	0.002	4.1	8.0	−0.009^*	0.002	2.2	4.3	−0.011^*	0.002	3.4	6.7
Black	−0.120^*	0.038			−0.138^*	0.034			−0.145^*	0.035
Hispanic	−0.078	0.040	2.0	3.9	−0.067	0.036	2.7	5.3	−0.069	0.037	3.0	5.9
Other minority	−0.018	0.076			0.012	0.070			−0.026	0.072
(Total)^†			20.3	39.7			32.7	63.8			28.4	55.6

Protein Density (% energy from protein)
Intercept	2.652^*	0.017			2.671^*	0.017			2.687^*	0.018
FFQ	0.344^*	0.068	6.5	38.5
4DFR					0.488^*	0.067	11.0	65.9
24HR									0.393^*	0.068	7.0	41.7
BMI	−0.002	0.002	0.6	3.3	−0.001	0.002	0.5	3.2	−0.001	0.002	0.4	2.3
Age	−0.002	0.002	0.04	0.2	−0.001	0.002	0.01	0.04	−0.003	0.002	0.1	0.7
Black	−0.100^*	0.037			−0.130^*	0.036			−0.133^*	0.037
Hispanic	−0.043	0.041	1.7	10.0	−0.035	0.040	2.8	17.0	−0.043	0.041	2.9	17.6
Other minority	−0.030	0.078			−0.006	0.075			−0.042	0.078
(Total)^†			8.7	52.1			14.4	86.1			10.4	62.3

BMI, body mass index; FFQ, food frequency questionnaire; 4DFR, four-day food record; 24HR, 24-hour dietary recall (3); UN, urinary nitrogen; Adj R², adjusted R² values (R² divided by log-biomarker correlation in reliability subsample).

Coefficient differs from zero at p=0.05 significance level

^†

Total – percent of variation explained by all variables. R² values for specific variables arise from analyses with only these regression variables, with subsequent rescaling so that these R² values add to the total regression R². R² values for race/ethnicity pertain to comparisons among the four groups (white, black, Hispanic, other minority).