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Diet Screener in the 2005 CHIS: Scoring Procedures

How Analytical Scoring Procedures Were Developed

Scoring procedures were developed to convert the individual respondent's screener responses to estimates of individual dietary intake for servings of fruits and vegetables and teaspoons of added sugar using USDA's 1994-96 Continuing Survey of Food Intakes of Individuals (CSFII 94-96) dietary recall data.

For servings of fruits and vegetables:

E(Fruits and Veg1/2) = b0 + b1(NFG1P1 + NFG2P2 + ... + NFG7P7)1/2

Servings of fruits and vegetables was square-root-transformed to approximate normality; NFGk is the usual number of times per day an individual consumed food group k; k indexes the 7 fruit and vegetable food groups. Pk is the median portion size of group k. We calculated weighted least-squares estimates of the regression coefficients b0 and b1 on the adults (aged 18 and above) in the CSFII 94-96 sample, stratifying by gender and excluding extreme exposure values.

Scoring Procedures

After excluding extreme and missing values, we performed the following steps with the CHIS dietary data to estimate the individual's intake of servings of fruits and vegetables.

  1. Estimation of NFGk: All reported frequencies were standardized to a common unit of time by converting them to daily frequencies.
    Time Period Reported NFGk: Daily Frequency
    Day As reported
    Week Reported frequency divided by 7
    Month Reported frequency divided by 30

For Fruit and Vegetable Intake:

  1. Estimation of Pk: The median age- and gender-specific portion sizes for each food were estimated from CSFII 94-96. The units were in Pyramid servings (Table 1).

    A Pyramid serving is defined by the U.S. Department of Agriculture in the 1992 Dietary Guidelines Food Guide Pyramid as:

    • vegetables: 1 cup raw leafy, 1/2 cup of other vegetables, or 3/4 cup vegetable juice; and
    • fruit: 1 whole fruit, 1/2 cup of cut-up fruit, or 3/4 cup fruit juice.

    More recently, the 2005 Dietary Guidelines measure fruits and vegetables in cup equivalents. See MyPyramid for definitions of cup equivalents.

    Both metrics are provided for these 2005 data.

    Table 1a. Median Portion Size (Pk) in Pyramid Servings* per Mention by Gender and Age for Fruits and Vegetables Analyses
    Food Group Age Group
    18-27 28-37 38-47 48-57 58-67 68-77 78-99
    Men
    100% fruit juice (P1) 2.000000 1.667500 1.335000 1.335000 1.334000 1.001000 1.001000
    Fruit (P2) 1.301000 1.301000 1.229571 1.227333 1.168000 1.168000 1.052333
    Salad (P3) 0.545000 0.708000 0.754500 0.750000 0.833500 0.750000 0.822500
    Fried potatoes (P4) 2.000000 2.000000 1.773000 1.710000 1.400000 1.250000 1.250000
    Other white potatoes (P5) 2.000000 2.000000 1.999000 1.999000 1.914000 1.544000 1.508000
    Dried beans (P6) 1.374000 1.047000 1.065000 1.227000 1.000000 1.000000 1.114000
    Other vegetables (P7) 0.750000 0.906000 0.974500 1.000000 1.000000 0.880000 0.833333
    Women
    100% fruit juice (P1) 1.500500 1.334000 1.334000 1.251250 1.019500 1.000500 1.000500
    Fruit (P2) 1.168000 1.168000 1.168000 1.168000 1.150500 1.083833 1.000000
    Salad (P3) 0.613500 0.572500 0.833333 1.000000 0.795500 0.625000 0.750000
    Fried potatoes (P4) 1.481000 1.365500 1.272000 1.400000 1.000000 1.026000 1.000000
    Other white potatoes (P5) 1.544000 1.544000 1.528000 1.544000 1.499000 1.516000 1.272000
    Dried beans (P6) 0.964000 0.684000 0.800000 0.687000 0.822000 0.807000 1.000000
    Other vegetables (P7) 0.702200 0.779333 0.792500 0.788500 0.774000 0.833000 0.856750
    Table 1b. Median Portion Size (Pk) in Cup Equivalents** per Mention by Gender and Age for Fruits and Vegetables Analyses
    Food Group Age Group
    18-27 28-37 38-47 48-57 58-67 68-77 78-99

    Men

    100% fruit juice (P1) 1.499160 1.250580 1.000980 1.000980 1.000176 0.750735 0.750735
    Fruit (P2) 0.999580 0.933450 0.867300 0.867300 0.867300 0.774916 0.657060
    Salad (P3) 0.272700 0.353970 0.377235 0.374963 0.416640 0.375000 0.411323
    Fried potatoes (P4) 0.721125 0.727700 0.641000 0.641000 0.548055 0.480750 0.499980
    Other white potatoes (P5) 1.000400 1.140030 0.999600 0.999600 0.999490 0.833175 0.754400
    Dried beans (P6) 0.717550 0.551540 0.566720 0.612360 0.500250 0.502285 0.575360
    Other vegetables (P7) 0.387675 0.473920 0.499840 0.500240 0.499905 0.460585 0.416899
    Women
    100% fruit juice (P1) 1.124370 1.000960 1.000176 0.938130 0.764776 0.750728 0.750434
    Fruit (P2) 0.749235 0.867300 0.844838 0.789970 0.742350 0.712640 0.620475
    Salad (P3) 0.306788 0.286335 0.416625 0.499950 0.397688 0.312469 0.374963
    Fried potatoes (P4) 0.509595 0.455110 0.448700 0.448700 0.394856 0.444260 0.444260
    Other white potatoes (P5) 0.782020 0.876945 0.771260 0.771260 0.749700 0.771260 0.644235
    Dried beans (P6) 0.492150 0.341550 0.430530 0.345763 0.430685 0.430530 0.500400
    Other vegetables (P7) 0.364468 0.395882 0.404303 0.408330 0.416913 0.436560 0.452214
  2. For Pyramid servings of fruits and vegetables, estimation of b0 and b1:
    The model is: E(Dietary Factor1/2) = b0 + b1 (NFG1P1 + NFG2P2 + ... + NFG7P7)1/2

    For Pyramid servings of fruits and vegetables, including and excluding French fries and dried beans, for each gender, the estimates of the parameters are:

    Table 2a. Estimated Regression Coefficients for Sum of Foods Predicting Pyramid Servings* of Different Versions of Daily Servings of Fruits and Vegetables, by Gender
    Parameter Men Women
    Summary Variable with French fries
    Intercept (b0) 0.906793 0.819559
    b1 0.758560 0.730865
    Summary Variable excluding French fries
    Intercept (b0) 0.940772 0.816265
    b1 0.739056 0.730219
    Summary Variable excluding French fries and beans
    Intercept (b0) 0.950228 0.813568
    b1 0.723395 0.723230
    Summary Variable excluding beans
    Intercept (b0) 0.884786 0.813994
    b1 0.761347 0.726001
    Table 2b. Estimated Regression Coefficients for Sum of Foods Predicting Different Versions of Daily Cup Equivalents of Fruits and Vegetables**, by Gender
    Parameter Men Women
    Summary Variable with French fries
    Intercept (b0) 0.666228 0.611844
    b1 0.770652 0.733890
    Summary Variable excluding French fries
    Intercept (b0) 0.706696 0.616033
    b1 0.742255 0.727761

    Summary Variable excluding French fries and beans

    Intercept (b0) 0.719659 0.618209
    b1 0.723629 0.718681
    Summary Variable excluding beans
    Intercept (b0) 0.671443 0.613051
    b1 0.758684 0.725692

For teaspoons of added sugar:

  1. Estimation of Pk: The median age- and gender-specific portion sizes in grams for each food were estimated from CSFII 94-96 (Table 3).
    Table 3. Median Portion Size (Pk) in Teaspoons*** per Mention by Gender and Age for Added Sugar Analyses
    Food Group Age Group
    18-27 28-37 38-47 48-57 58-67 68-77 78+
    Men
    Regular soda (P1) 11.246397 9.221880 9.221880 9.221880 9.214440 9.125268 9.115360
    Fruit drinks (P2) 10.600000 8.636250 8.565000 8.565000 6.276880 5.700512 5.540320
    Cookies, cake, pie (P3) 5.083032 4.762847 4.582705 4.426306 4.552020 4.216712 3.761836
    Ice cream (P4) 7.046725 5.905380 6.783700 5.858650 5.858650 4.759920 3.478629
    Women
    Regular soda (P1) 9.221880 9.221880 9.184695 9.125268 8.041256 7.684900 9.120314
    Fruit drinks (P2) 8.246250 7.773757 6.276880 6.218740 6.251570 5.353125 5.300000
    Cookies, cake, pie (P3) 3.945000 3.533487 3.649440 3.595380 3.866728 3.315540 3.027309
    Ice cream (P4) 5.858650 5.546760 5.814600 4.933600 4.560570 3.920450 3.920450
  2. For teaspoons of added sugar, estimation of b0 and b1:
    The model is: E(Dietary Factor1/3) = b0 + b1 (NFG1P1 + NFG2P2 + ... + NFG4P4)1/3

    For teaspoons of added sugar, estimates of the parameters are:

    Table 4. Estimated Regression Coefficients for Sum of Foods Predicting Teaspoons of Added Sugar***, by Gender
    Parameter Men Women
    Intercept (b0) 1.566813 1.481876
    b1 0.555082 0.514735

    * Using 1992 Food Guide Pyramid definitions of servings.

    ** Using 2005 MyPyramid definitions of cups of fruits and vegetables.

    *** Using 2005 MyPyramid database.

Last Modified: 11 Apr 2014