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Equations estimated in the NHANES 2003-2006, using SAS PROC REG

For cup equivalents of fruits and vegetables:

E ([Fruits and Veg]1/2) = b0+ b1([NFG1P1 + NFG2P2+... + NFG10P10]1/2)

Cup equivalents of fruits and vegetables were square-root-transformed to approximate normality; NFGk is the usual number of times per day an individual consumed food group k; Pk is the median portion size in fruit and vegetable cup equivalents of group k; and k indexes the ten fruit and vegetable food groups. We calculated weighted least-squares estimates of the regression coefficients b0 and b1 in the NHANES 2003-2006 samples, stratifying by sex, and excluding extreme exposure values.

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For cup equivalents of fruits:

E ([Fruits]1/2) = b0+ b1([NFG1P1 + NFG2P2]1/2)

Cup equivalents of fruits was square-root-transformed to approximate normality; NFGk is the usual number of times per day an individual consumed food group k; Pk is the median portion size in fruit cup equivalents of group k; and k indexes the two fruit food groups: fruit, and 100% fruit juices. We calculated weighted least-squares estimates of the regression coefficients b0 and b1 in the NHANES 2003-2006 samples, stratifying by sex, and excluding extreme exposure values.

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For cup equivalents of vegetables:

E ([Veg]1/2) = b0+ b1([NFG3P3 + NFG4P4+... + NFG10P10] 1/2)

Cup equivalents of vegetables was square-root-transformed to approximate normality; NFGk is the usual number of times per day an individual consumed food group k; Pk is the median portion size in vegetable cup equivalents of group k; and k indexes the eight vegetable food groups. We calculated weighted least-squares estimates of the regression coefficients b0 and b1 in the NHANES 2003-2006 samples, stratifying by sex, and excluding extreme exposure values.

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For cup equivalents of dairy:

E ([Dairy]1/2) = b0+ b1([NFG1P1+ NFG2P2+...+ NFG4P4] 1/2)

Cup equivalents of dairy were square-root-transformed to approximate normality; NFGk is the usual number of times per day an individual consumed food group k; Pk is the median portion size in dairy cup equivalents of group k; and k indexes the four dairy food groups. We calculated weighted least-squares estimates of the regression coefficients b0 and b1 on the NHANES 2003-2006 samples, stratifying by sex, and excluding extreme exposure values.

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For teaspoons of added sugars:

E ([Added Sugars].33) = b0+ b1([NFG1P1+ NFG2P2+...+ NFG13P13].33)

Teaspoons of added sugars were cube-root-transformed to approximate normality; NFGk is the usual number of times per day that an individual consumed food group k; Pk is the median portion size in added sugars teaspoons of group k; and k indexes the thirteen added sugars food groups.

We calculated weighted least-squares estimates of the regression coefficients b0 and b1 in the NHANES 2003-2006 samples, stratifying by sex, and excluding extreme exposure values.

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For teaspoons of added sugars from sugar-sweetened beverages:

E ([Added Sugarsssb].5) = b0+ b1([NFG1P1+ NFG2P2+ NFG3P3].5)

The dependent variable added sugars from sugar-sweetened beverages included the following beverages: sodas, fruitades/sports drinks, and sugar in coffee/tea. Teaspoons of added sugars were square-root-transformed to approximate normality; NFGk is the usual number of times per day that an individual consumed food group k; Pk is the median portion size in added sugars teaspoons of group k; and k indexes the three sugar-sweetened beverage food groups.

We calculated weighted least-squares estimates of the regression coefficients b0 and b1 in the NHANES 2003-2006 samples, stratifying by sex, and excluding extreme exposure values.

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For ounce-equivalents of whole grains:

E ([Whole Grains] 1/2) = b0 + b1 (NFG1P1) + b2(NFG2P2 ) + ... + b 9(NFG9P9)

Ounce-equivalents of whole grains were square-root-transformed to approximate normality; NFGk is the usual number of times per day an individual consumed food group k; Pk is the median portion size in whole grain ounce-equivalents of group k; and k indexes the nine whole grain food groups: hot cereals (2 groups), cold cereals (4 groups), brown rice, whole grain bread, and popcorn.

We calculated weighted least-squares estimates of the regression coefficients b0 and bk, k = 0, ..., 9 on the NHANES 2003-2006 samples, stratifying by sex, and excluding extreme exposure values.

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For grams of fiber:

E ([Fiber] 1/4) = b0 + b1(NFG1P1) + b2(NFG2P2 ) + ... + b29 (NFG29P29)

Grams of fiber were quarter-root-transformed to approximate normality; NFGk is the usual number of times per day an individual consumed food group k; Pk is the median portion size in grams of group k; and k indexes the 28 food groups. Two food groups, tomato sauce, and dried beans, were frequently consumed in mixed dishes. Because we wanted to represent only the particular food, we estimated the number of grams of tomatoes and legumes, respectively, in these mixed dishes. For tomato sauce, this was done by multiplying the MPED 1 cup equivalent by 171 (1 MPED = 171 grams). For legumes, this was done by estimating the MPED one cup equivalent for legumes and multiplying by 212 (1 MPED = 212 grams).

We calculated weighted least-squares estimates of the regression coefficients b0 and bk, k = 0,..., 29 on the NHANES 2003-2006 samples, stratifying by sex, and excluding extreme exposure values. We first included all 29 food groups in the regression model. After examining the results, we dropped food groups that failed to attain statistical significance at α = 0.25 to form more parsimonious final models. In the fiber model, soda and sugar in coffee/tea were dropped for men, and salad and sugar in coffee/tea were dropped for women.

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For milligrams of calcium:

E ([Calcium] 1/4) = b0 + b1 (NFG1P1) + b2(NFG2P2 )+ ... + b 29(NFG29P29)

Milligrams of calcium were quarter-root-transformed to approximate normality; NFGk is the usual number of times per day an individual consumed food group k; Pk is the median portion size in grams of group k; and k indexes the 29 food groups. Two food groups, tomato sauce, and dried beans, were frequently consumed in mixed dishes. Because we wanted to represent only the particular food, we estimated the number of grams of tomatoes and legumes, respectively, in these mixed dishes. For tomato sauce, this was done by multiplying the MPED 1 cup equivalent by 171 (1 MPED = 171 grams). For legumes, this was done by estimating the MPED one cup equivalent for legumes and multiplying by 212 (1 MPED = 212 grams).

We calculated weighted least-squares estimates of the regression coefficients b0 and bk, k = 0, ..., 29 on the NHANES 2003-06 samples, stratifying by sex, and excluding extreme exposure values. We first included all 29 food groups in the regression model. After examining the results, we dropped food groups that failed to attain statistical significance at α = 0.25 to form more parsimonious final models. In the calcium model, popcorn, brown rice, soda, sugar in coffee/tea, and other potatoes were dropped for men; and popcorn, brown rice, fruitades/sports drinks, doughnuts, and tomato sauce were dropped for women.

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Last Modified: 11 Apr 2014