Multifactor Screener in OPEN: Scoring Procedures & Results

How Analytical Scoring Procedures Were Developed

Scoring procedures were developed to convert a respondent's screener responses to estimates of individual dietary intake for percentage energy from fat, grams of fiber, and servings of fruits and vegetables, using USDA's 1994-96 Continuing Survey of Food Intakes of Individuals (CSFII 94-96)dietary recall data. The following equations were estimated in the CSFII 94-96:

For percentage energy from fat and fiber:

E(Dietary Factor) = b0+ b1NFG1P1 + b2NFG2P2 + … + b19NFG19P19

E(Dietary Factor) indicates the expected values for percentage energy from fat and for fiber, and assumes a normal distribution. In the CSFII 94-96 dataset percentage energy from fat was normally distributed. However, fiber was positively skewed and required a cube-root transformation 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 19 food groups. These 19 food groups were formed to reflect the same food groups on the screener. We calculated weighted least-squares estimates of the regression coefficients bk, k = 0, …, 19 on CSFII 94-96 adults aged 18 and above, stratifying by gender and excluding extreme exposure values. We first included all 19 food groups in the regression model. After examining the results, we dropped food groups that failed to attain statistical significance at the α = 0.25 level to form more parsimonious final models. In both the percentage energy from fat model and the fiber model, the lettuce food group was dropped. Because of the complex survey design, the analysis was performed using SUDAAN (RTI Inc., Research Triangle Park, NC).

For Pyramid servings of fruits and vegetables (defined by USDA in the 1992 Dietary Guidelines Food Guide Pyramid):

E([Fruits and Veg]1/2) = b0 + b1 ([NFG1P1 + NFG2P2 + … + NFG7P7]1/2)

Pyramid 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 7 fruit and vegetable food groups. We calculated weighted least-squares estimates of the regression coefficients b0 and b1 on the adults in the CSFII 94-96 sample, stratifying by gender and excluding extreme exposure values.

Scoring Procedures

1. Estimation of NFGk: Express each reported frequency as a daily average. To do this, standardize the midpoint of each frequency category to the number of times per day.

View Frequency Table

Frequency Response Times Per Day
Never 0.0
1-3 times per month 0.067
1-2 times per week 0.214
3-4 times per week 0.5
5-6 times per week 0.786
1 time per day 1.0
2 times per day 2.0
3 times per day 3.0
4 or more times per day 4.5

2. Estimation of Pk: The median age- and gender-specific portion sizes for each food were estimated from CSFII 94-96. For percentage energy from fat and fiber variables, the units were in grams (Tables 1-2); for fruit and vegetable servings variables, the units were in Pyramid servings (Table 3).

A Pyramid serving is defined by the U.S. Department of Agriculture in the Dietary Guidelines Food Guide Pyramid (used from 1992-2004) as:

  • vegetables: 1 cup raw leafy, ½ cup of other vegetables, or ¾ cup vegetable juice; and
  • fruit: 1 whole fruit, ½ cup of cut-up fruit, or ¾ cup fruit juice.

Note: current dietary guidance uses cups rather than servings.

Table 1: Median Portion Size (Pk) in Grams per Mention by Age for Percentage Energy from Fat and Fiber Analyses: Men

View Table 1

Food Group Age Group
18-27 28-37 38-47 48-57 58-67 68-77 78-99
Men
Cold cereals (P1) 74.666667 61.500000 57.500000 56.000000 46.000000 39.000000 33.000000
Whole milk (P2) 305.000000 259.250000 306.710000 244.000000 244.000000 244.000000 203.333333
2% milk (P3) 259.250000 305.000000 244.000000 244.000000 244.000000 183.000000 183.000000
1% milk (P4) 341.600000 245.000000 245.000000 244.000000 213.500000 223.666667 183.000000
Skim milk (P5) 366.666667 250.000000 250.000000 245.000000 214.375000 198.937500 160.725000
Bacon or sausage (P6) 25.000000 40.250000 32.000000 32.000000 27.000000 26.000000 24.000000
Hotdogs (P7) 114.000000 85.500000 88.000000 114.000000 57.000000 57.000000 57.000000
Whole grain bread (P8) 56.000000 54.000000 52.000000 52.000000 51.000000 48.250000 48.000000
100% fruit juice (P9) 372.000000 311.250000 249.000000 249.000000 248.000000 186.750000 186.750000
Fruit (P10) 131.750000 128.000000 123.200000 127.500000 122.000000 118.000000 114.250000
Salad dressing (P11) 23.543333 23.626667 22.030000 27.500000 24.585000 19.285000 15.600000
Fried potatoes (P12) 112.500000 114.000000 100.000000 100.000000 85.500000 85.500000 97.000000
Other white potatoes (P13) 210.000000 196.000000 184.000000 161.000000 145.000000 127.000000 107.000000
Dried beans (P14) 180.000000 130.000000 172.000000 172.000000 158.125000 175.000000 170.100000
Other vegetables (P15) 60.013333 73.000000 74.063333 79.833333 76.500000 73.000000 67.520909
Pasta (P16) 330.000000 280.000000 280.000000 247.500000 280.000000 210.000000 210.00000
Nuts (P17) 31.625000 58.000000 35.500000 54.665000 39.250000 17.130000 35.916667
Chips (P18) 40.000000 40.000000 31.895000 30.000000 26.000000 21.000000 17.500000

Table 2: Median Portion Size (Pk) in Grams per Mention by Age for Percentage Energy from Fat and Fiber Analyses: Women

View Table 2

Food Group Age Group
18-27 28-37 38-47 48-57 58-67 68-77 78-99
Women
Cold cereals (P1) 50.000000 49.500000 44.000000 43.500000 33.000000 33.000000 33.500000
Whole milk (P2) 244.000000 244.000000 244.000000 244.000000 198.250000 198.250000 196.400000
2% milk (P3) 244.000000 244.000000 244.000000 244.000000 183.000000 183.000000 152.500000
1% milk (P4) 244.000000 244.000000 183.000000 152.500000 183.000000 183.000000 218.583333
Skim milk (P5) 245.000000 245.000000 244.800000 229.690000 196.000000 183.750000 183.750000
Bacon or sausage (P6) 26.000000 25.000000 24.000000 24.000000 18.000000 19.500000 16.000000
Hotdogs (P7) 57.000000 57.000000 57.000000 114.000000 57.000000 57.000000 57.000000
Whole grain bread (P8) 50.000000 48.000000 47.500000 45.000000 45.000000 42.400000 34.000000
100% fruit juice (P9) 280.125000 249.000000 248.800000 233.250000 189.755000 186.600000 186.700000
Fruit (P10) 118.000000 118.000000 118.000000 118.000000 118.000000 112.427143 109.000000
Salad dressing (P11) 17.140000 20.626667 23.020000 21.873333 22.035000 18.335000 10.210000
Fried potatoes (P12) 79.500000 70.000000 70.000000 70.000000 66.000000 70.000000 64.000000
Other white potatoes (P13) 122.000000 127.000000 116.000000 122.000000 105.000000 105.000000 105.000000
Dried beans (P14) 126.500000 89.000000 126.500000 126.500000 126.500000 126.500000 173.000000
Other vegetables (P15) 53.750000 61.625000 61.500000 61.532500 63.165000 67.142857 71.333333
Pasta (P16) 217.500000 217.500000 182.525000 185.000000 165.000000 160.000000 175.000000
Nuts (P17) 18.000000 32.000000 20.655000 21.265000 18.250000 11.250000 25.500000
Chips (P18) 28.000000 24.333333 27.000000 26.000000 20.000000 18.000000 14.000000

Table 3a. Median Portion Size (Pk) in Pyramid Servings * per Mention by Gender and Age for Fruits and Vegetables Analyses

View Table 3a

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 3b. Median Portion Size (Pk) in Cup Servings ** per Mention by Gender and Age for Fruits and Vegetables Analyses

View Table 3b

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 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

3. For percentage energy from fat and fiber (grams), estimation of bk, k = 0, ..., 19: the values for each parameter, for each gender, are in the following table:

Table 4. Estimated Regression Coefficients for Foods as Predictors of Percentage Energy from Fat and Grams of Fiber, by Gender

View Table 4

Parameter Men Women
Percentage Energy from Fat Fiber (cube root) Percentage Energy from Fat Fiber (cube root)
Intercept (b0) 31.93268 2.08423 31.36357 1.89847
Cold cereals (b1) -0.02672 0.00209 -0.05797 0.00389
Whole milk (b2) 0.00653 0.00013 0.00842 0.00009
2% milk (b3) 0.00215 0.00013 0.00272 0.00011
1% milk (b4) -0.00149 0.00022 -0.00196 0.00024
Skim milk (b5) -0.00841 0.00028 -0.00867 0.00034
Bacon or sausage (b6) 0.13831 -0.00139 0.23128 -0.00201
Hotdogs (b7) 0.04078 0 0.10160 -0.00141
Whole grain bread (b8) 0 0.00283 0 0.00337
100% fruit juice (b9) -0.00533 0.00019 -0.01011 0.00025
Fruit (b10) -0.00932 0.00103 -0.01201 0.00105
Salad dressing (b11) 0.15036 0 0.23974 0
Fried potatoes (b12) 0.02734 0.00160 0.04272 0.00156
Other white potatoes (b13) 0.00580 0.00071 0.00618 0.00066
Dried beans (b14) -0.00526 0.00275 -0.00608 0.00380
Other vegetables (b15) 0 0.00084 0 0.00093
Pasta (b16) -0.00504 0.00075 -0.00540 0.00082
Nuts (b17) 0.12454 0.00546 0.26018 0.00603
Chips (b18) 0.05376 0.00528 0.13144 0.00456

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

The model is: E([Fruits and Veg]1/2) = b0 + b1 ([NFG1P1 + NFG2P2 + … + NFG7P7]1/2)

For Pyramid servings of fruits and vegetables without French fries, estimation of b0 and b1:

The model is: E([F&V not FF]1/2) = b0 + b1 ([NFG1P1 + NFG2P2 + … + NFG7P7]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 Pyramid Servings of Total Fruits and Vegetables and Fruits and Vegetables Excluding French Fries, by Gender

View Table 5

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

For cups of fruits and vegetables (2005 MyPyramid definition), including and excluding French fries, for each gender, the estimates of the parameters are:

Table 6. Estimated Regression Coefficients for Sum of Foods Predicting Cups of Total Fruits and Vegetables and Fruits and Vegetables Excluding French Fries, by Gender

View Table 6

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

Download the SAS program to compute the variables

Validation Results

Staff in the Epidemiology and Genomics Research Program's Risk Factor Assessment Branch have assessed the validity of the Multifactor Screener in several studies: NCI's OPEN Study, the Eating at America's Table Study (EATS), and the joint NIH-AARP Diet and Health Study. In all studies, multiple 24-hour recalls in conjunction with a measurement error model were used to assess validity. In general, the validation results reflect the Multifactor Screener's hierarchical design -- fruit and vegetable intake was estimated best by the screener, followed by percentage energy from fat, and lastly grams of fiber.

In the OPEN Study, estimates of median intake were:

  • Pyramid Servings of Fruits and Vegetables:
    • Men: recalls - 6.3; screener - 5.3;
    • Women: recalls - 5.4; screener - 4.7.
  • Percentage Energy from Fat:
    • Men: recalls - 31.8; screener - 32.0;
    • Women: recalls - 32.0; screener - 30.5.
  • Fiber:
    • Men: recalls - 21.2; screener - 18.3;
    • Women: recalls - 16.5; screener - 14.1.

These validation results suggest that dietary exposure estimates computed from the Multifactor Screener may be useful to compare subgroup means, especially for populations consuming mainstream diets. The estimates may be less useful for populations with more ethnic diets, including Asian and possibly Latino populations.

At the individual level, correlations between the screener and estimated true intake ranged from 0.54 (fiber for men) to 0.76 (Pyramid servings of fruits and vegetables for women); about 25 to 50 percent of the variability in the true intake will be captured by the screener questions. Thus, although significant error may be associated with these estimates of diet, we believe the exposure estimates still substantially reflect what individuals are actually consuming.

Validation results are reported in detail in: