Data Available from the Diet History Questionnaire III (DHQ III)

Calculating the Healthy Eating Index (HEI)-2015

The Healthy Eating Index-2015 (HEI-2015) is the latest iteration of the HEI. The HEI is a measure of diet quality, independent of quantity that can be used to assess compliance with The U.S. Dietary Guidelines for Americans and monitor changes in dietary patterns. The HEI also is a valuable tool for epidemiologic and economic research and can be used to evaluate nutrition interventions and consumer nutrition education programs. It can also be used to determine the quality of a given dietary pattern, set of foods, or menu.

The Total Daily Results output file includes the following variables:

• HEI-2015 total score
• Individual component scores
• Individual component density values

View Total Daily Results Output File [CSV - 11 KB]

More information about the HEI is available.

Analysis Files

The DHQ III analysis program is fully integrated into the DHQ III web-based software.  Nutrient and food group intakes based on questionnaire responses are automatically calculated and available on the DHQ III Researcher website. Note that within the analysis files, nutrient estimates from foods/beverages and dietary supplements are reported separately.

DHQ III analyses produce 4 different analysis files:

1. Total Daily Results file:  Total nutrient and food group intake, and the Healthy Eating Index-2015 data for each respondent based on foods and supplements reported.
2. Detailed Analysis file:  Nutrient and food group intake data by respondent for each food and supplement reported.
3. Excel formatted Answers file: Responses to each question on DHQ III by respondent in a spreadsheet format easily read in Excel.
4. Raw formatted Answers file: Responses to each question on DHQ III by respondent in a single column for easy import into SAS, SPSS, or other statistical program.

The data in each file is available in CSV (Comma Separated Values) format:
Download Sample Analysis Results File [CSV - 6 KB]

The following data columns are included in the Total Daily Results and Detailed Analysis files:

• Respondent ID
• Record Number
• Sex
• Age
• Birth Date
• Questionnaire Date
• Nutrient Estimates (a column of data per nutrient in the Nutrient Database)
• Percent of Energy from Macronutrients
• Food Group Estimates
• Nutrient Estimates from Supplements
• Other Questions

The following data columns are included in the Excel formatted Answers files:

• Study ID
• Respondent ID
• Questionnaire Date
• Question IDs (a column of data per question asked in the questionnaire)

Data Quality and Cleaning

There are no data cleaning or exclusion programs built into the software. Researchers can decide, based on break offs, energy, or other considerations, which respondents to exclude from analyses. Different investigators clean data in different ways: some like calorie exclusions, some like exclusions based on percentile cutpoints of nutrients or missing data, some like to transform data and then exclude, others want to exclude those respondents who did not take the task seriously (however that is defined). By looking at output files, one can write a program to check issues related to whether an individual always checks the same frequency or portion size. It is our experience that it is difficult to discern these types of errors from energy exclusions. FFQ data can be messy for some respondents and prone to measurement error for all.

Coding Algorithms

Additionally, default settings for when frequency questions are asked for "in season" vs. "rest of year," are 1/4 vs 3/4 of a calendar year. For frequency questions asked with the terminology "in summer/winter" vs. "rest of year" the settings are 1/3 vs 2/3 of the year.

Citing DHQ in Publications and Presentations

In order to show and maintain support for DHQ, documenting its use through publications is extremely useful to the National Cancer Institute (NCI).

To achieve this, we invite investigators to include the following sentence in the methods section of their manuscripts: Dietary intake data were collected and analyzed using the Diet History Questionnaire (DHQ), version, developed by the National Cancer Institute, Bethesda, MD.

Additionally, when citing DHQ, please include a link to the DHQ website, e.g., https://epi.grants.cancer.gov/dhq3 for DHQIII.