The Pictorial DHQ is an adapted version of the validated Diet History Questionnaire (DHQ)¹ developed by staff at the National Cancer Institute. It differs from the DHQ in the following ways:

-Web-based: the computer-based version of the DHQ captures data entered by the participant.

-Graphical displays of food portions: Since portion size estimation is associated with a large amount of error in dietary reporting, the accuracy of responses obtained from food frequency questionnaires (FFQ) may be significantly enhanced by providing pictorial representations of food quantities.

VisualDHQ takes about 1 hour to complete and was designed to be easy to use.

- Efficiency: Data collected by the participant will be immediately available for analysis or review of results with the participant. This is a significant improvement over conventional methods, where data must be entered by a third party or scanned and verified. In all, VisualDHQ analysis provides feedback for 75 nutrients and constituents and 30 food groups. VisualDHQ analysis is performed using Diet*Calc software, an analysis program created by NCI specifically for use with the Dietary History Questionnaire.

- Usability: Low literacy, language barriers, and poor eyesight are often barriers to completion of paper-based questionnaires, thereby reducing external validity of research studies. By providing pictures of each of the foods, participants who have trouble reading English can successfully complete assessments.

- Quality Assurance: Electronic data capture greatly reduces missing data problems as participants are prompted to provide a response to each question. The computer-based approach also eliminates transcription errors associated with scanning or data entry by a third party.

1. Subar AF, Thompson FE, Kipnis V, et al. Comparative validation of the block, willett, and national cancer institute food frequency questionnaires: The eating at America's table study. Am J Epidemiol. 2001;154:1089-1099.