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Fruit and Vegetable Screener: 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 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 Veg]1/2) = b0+ b1([NFG1P1 + NFG2P2 + … + NFG8P8]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; Pk is the median portion size of group k; and k indexes the 8 fruit and vegetable food groups. 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 exclusion of 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

  2. 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 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.
    Table 1. 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
    Tomato sauce/salsa (P8) 0.626000 0.587000 0.579000 0.607000 0.533600 0.606667 0.405000
    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
    Tomato sauce/salsa (P8) 0.410000 0.400000 0.402000 0.396000 0.477500 0.356000 0.252000

  3. For Pyramid servings of fruits and vegetables, estimation of b0 and b1:

    The model is: E([Dietary Factor]1/2) = b0 + b1 ([NFG1P1 + NFG2P2 + … + NFG8P8]1/2)

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

    Table 5. Estimated Regression Coefficients for Sum of Foods Predicting Servings of Different Versions of Daily Servings of Fruits and Vegetables, by Gender
    Parameter Men Women
    Summary Variable with French fries
    Intercept (b0) 0.755105 0.711444
    b1 0.815466 0.775801
    Summary Variable excluding French fries
    Intercept (b0) 0.771919 0.694500
    b1 0.806806 0.783053
    Summary Variable excluding French fries and beans
    Intercept (b0) 0.773746 0.691176
    b1 0.796528 0.776859
    Summary Variable excluding beans
    Intercept (b0) 0.729300 0.703858
    b1 0.820729 0.772394

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Last Modified: 11 Apr 2014