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₍N_FG1P₁ + N_FG2P₂ + ... + N_FG8P₈)^1/2

Servings of fruits and vegetables was square-root-transformed to approximate normality; N_FGk is the usual number of times per day an individual consumed food group k; P_k 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 N_FGk: 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 P_k: 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 (P_k) 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 (N_FG1P₁ + N_FG2P₂ + ... + N_FG8P₈)^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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