Diet History Questionnaire: Format Definitions
Many fields in the Diet History Questionnaire (DHQ) use the same coding scheme or format. A format defines the number of choices for a question and the meaning of each choice. For example, the response choices for "How often did you eat..." questions are coded using one of several formats. The formats are set in the Questionnaire Data Dictionary (QDD). You may modify the existing formats using the dictionary editor in Diet*Calc.
Frequency formats are used for questions that ask "How often did you eat/drink...."
Size formats are used to code serving size questions, i.e., "When you ate (food), how much did you usually eat?"
"Filled in" and "left blank" codes are used when the respondent is asked to mark an oval if appropriate (not filling in the oval is a valid response and is not a skip for this type of question). For example, some DHQ questions provide a list of choices and instruct the respondent to "mark as many as apply."
Proportion formats are used to code questions that ask the respondent to specify how often (in fractions) the food was of a specific type. For example, the question "How often were your fruit drinks diet or sugar-free drinks?" has valid responses of "almost never or never", "about 1/4 of the time", "about 1/2 of the time", "about 3/4 of the time", and "almost always or always."
Duration format is used in supplement questions to indicate length of time, for example, "For how many years have you taken multi-vitamins?"