Classifying Cereal Data
The DSQ includes questions about cereal intake and allows respondents up to two responses on which cereals they consume. We classified each cereal reported first by hot or cold, and then along four dimensions: density of added sugars, whole grains, fiber, and calcium.
In the scoring algorithms, hot and cold cereals have different portion sizes. In addition, all categories have different regression coefficients that relate them to the various exposures. Initial coding of the cereal data must:
- Classify each by hot or cold.
- Classify each by nutrient density (nutrient/100 grams). We classified all hot and cold cereals reported on the DSQ in the NHANES 2009-10 into categories based on their nutrient density of four exposures: added sugars, whole grains, fiber, and calcium. The density categorization was based on the cereal composition and not the absolute frequency of reported consumption. Thus each cereal reported is coded along the following attributes: hot or cold; category for added sugars; category for whole grains; category for fiber; and category for calcium.
- Weight each according to order of report. For those respondents who reported two different cereal types, we assumed that the first cereal reported was the most frequently consumed and the second was less frequently consumed. Accordingly, we weighted the first cereal at 0.75 and the second at 0.25. For those who reported only one cereal type, no weighting was necessary. These weights were applied to all relevant cereal categories in the scoring algorithms.
Following are the classification criteria for cereal by hot or cold and by nutrient density. Note that each cereal may fall in different n-tiles for different nutrients.
|Type of Cereal||Density (tsp added sugars/100 grams)||No. of cereals|
|Hot cereals: no added sugars||0||33|
|Hot cereals: any added sugars||> 0||11|
|Cold cereals: 1st quartile added sugars||< 3.0||71|
|Cold cereals: 2nd quartile added sugars||3.01 to 5.25||68|
|Cold cereals: 3rd quartile added sugars||5.26 - 9.0||71|
|Cold cereals: 4th quartile added sugars||> 9.0||69|
|Type of Cereal||Density (ounce-equivalents of whole grains/100 grams)||No. of cereals|
|Hot cereals: no whole grain||0||12|
|Hot cereals: any whole grain||> 0||32|
|Cold cereals: no whole grain||0||88|
|Cold cereals: 2nd quartile whole grain||0.06 - 1.077||51|
|Cold cereals: 3rd quartile whole grain||1.07705 - 1.82||69|
|Cold cereals: 4th quartile whole grain||> 1.82||71|
|Type of Cereal||Density (grams of fiber/100 grams)||No. of cereals|
|Hot cereals: 1st tertile fiber||< 1.0||15|
|Hot cereals: 2nd tertile fiber||1.01 - 1.7||13|
|Hot cereals: 3rd tertile fiber||> 1.7||16|
|Cold cereals: 1st quartile fiber||< 3.1||69|
|Cold cereals: 2nd quartile fiber||3.103 - 5.99||69|
|Cold cereals: 3rd quartile fiber||6.0 - 9.99||72|
|Cold cereals: 4th quartile fiber||> 10.0||69|
|Type of Cereal||Density (milligrams of calcium/100 grams)||No. of cereals|
|Hot cereals: 1st tertile calcium||< 9.99||18|
|Hot cereals: 2nd tertile calcium||10-64||11|
|Hot cereals: 3rd tertile calcium||> 65||15|
|Cold cereals: 1st quartile calcium||< 24.9||70|
|Cold cereals: 2nd quartile calcium||25.0 - 46.99||70|
|Cold cereals: 3rd quartile calcium||47.0 - 332.99||68|
|Cold cereals: 4th quartile calcium||> 333||71|
Cereal data can be reported in different formats. The format used in the NHANES DSQ was 8-digit FNDDS food codes. Table 5 (XLS | CSV) shows the food codes and attributes for the cereals reported in the 2009-10 NHANES.
Cereal data reported on the self-administered web is in a character (i.e. letters) format. Table 6 shows the food codes and attributes for the cereal choices in the self-administered web version of the questionnaire.
Last Modified: 03 Sep 2013