DHQ*Web is a logical extension of the original machine-readable paper-and-pencil version of the Diet History Questionnaire. The Web-based version is identical in content to the original DHQ. By automating the DHQ and providing it 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.
We have had no formal large validation study of the Web-based DHQ, nor have we conducted a study comparing responses of the Web versus paper versions. Researchers will have to rely on our past research for the paper version as a measure of validation. DHQ*Web has, however, undergone 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.