The Web-based versions of DHQ II and C-DHQ II are identical in content to the paper forms. By automating the DHQ II and providing versions on the Web for public use, researchers have another tool to collect and analyze food frequency questionnaire data. DHQ*Web takes advantage of what automated and electronic questionnaires are able to do -- respondents follow automated skip patterns, are queried to complete all questions before proceeding to the next, navigate within the instrument to correct or modify responses, and can log in at any time to complete the questionnaire, starting where they left off. DHQ*Web provides efficiency with respect to data quality because respondents cannot complete the questionnaire with missing or inconsistent responses. The data from DHQ*Web can be analyzed using our Diet*Calc software.
NCI has not conducted a formal large validation study of the web-based DHQ II. Researchers will have to rely on our past research for the paper version as a measure of validation. Beasley et al. (Public Health Nutrition2008;12:651-59) however, conducted a study comparing responses of the Web versus paper versions of DHQ I and found few differences. The first version of the DHQ*Web underwent two rounds of usability testing in which the look and flow were modified and refined based on respondents' experience and suggestions. In general, respondents were easily able to complete the instrument and it appears from our small usability study samples that DHQ*Web can be completed in less time than the paper-and-pencil version.
The DHQ-II comes in four different versions:
- Past year, with portion size (our standard FFQ format): asks about intake in the past year and includes questions about portion size.
- Past year, without portion size: asks about usual intake in the past year and excludes questions about portion size.
- Past month, with portion size: asks about intake in the past month and includes questions about portion size.
- Past month, without portion size: asks about usual intake in the past month and excludes questions about portion size.
- C-DHQ II: Past month and past year, with portion size: asks about intake in the past month and past year and includes questions about portion size.
- The forms and codebook are available on the C-DHQ II Web site.
You may view demonstrations of DHQ*Web both for the U.S. and Canadian versions; the only versions available for demonstration are the version that query the past year with portion sizes.
If you are interested in using any of the versions of DHQ*Web you can do so by submitting a request for a study and you will receive a confirmation that it has been received. You will hear from a staff member within two weeks following your request. If for some reason you do not hear from our staff, please contact us at email@example.com.