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Epidemiology and Genomics Research Program

Diet History Questionnaire: Error Corrected in the 2002 Questionnaire Data Dictionary

Alternate Version Available

You are viewing the web site for the original version of the DHQ. The latest version for the U.S. is the DHQ III; however, DHQ III does not yet have a Canadian version. The Canadian version of DHQ II is still available.

Diet*Calc uses the information in the questionnaire data dictionary (*.qdd files) to determine how to analyze the questionnaire data. An error was discovered in the dhq1.2002.qdd. This QDD is the data dictionary that has been distributed for use with OSC forms and data entry since March 2004. This problem affects the calculation of estimates from multi-vitamins. It does not affect any of the nutrient estimates from food sources. This problem will only occur if you are using dhq1.2002.qdd, or a customized QDD which uses letters to code frequency in your data file.

Description of Problem

Question 137: How often did you take One-a-day-, Theragran-, or Centrum-type multivitamins?

Was incorrectly coded as:
a = never
b = less than 1 day per month
c = 1-3 days per month
d = 1-3 days per week
e = 4-6 days per week
f = every day
Correct coding is:
a = less than 1 day per month
b = 1-3 days per month
c = 1-3 days per week
d = 4-6 days per week
e = every day

Impact on Analyses

If the respondent answered "less than 1 day per month", they were assigned the frequency for "never". If they answered "every day", they were assigned the frequency for "4-6 days per week".

In the calculations, the difference in the values is:

Text on Questionnaire Value in Original QDD (dhq1.2002.qdd) Value using Revised QDD (dhq1.2002.rev02112005.qdd)
Less than 1 day per month 0 0.5 per month
1-3 days per month 0.5 per month 2.02 per month
1-3 days per week 2.02 per month 2 per week
4-6 days per week 2 per week 5 per week
Every day 5 per week 1 per day

Download the Revised Files

Questionnaire Data Dictionary: dhq1.2002.rev02112005.qdd [QDD - 67 KB]

Coding Information:
dhq1.2002.codebook.pdf [PDF - 1.2 MB]
dhq1.2002.codebook.doc [DOC - 739 KB]

Instructions for Correcting a Customized QDD: instructions_multivitamins.pdf [PDF - 23 KB]