Dietary variables, and information about the variables, are stored in different data and documentation files. You will use these files to identify dietary recall variables of interest and their file locations, identify food frequency variables and their file locations, identify dietary supplement variables and their file locations, and identify correct sample weights and their file locations. Reviewing the data file documents also is an essential part of learning about dietary variables.
Dietary recall variables and information about the variables are stored within the Examination data files. To identify dietary recall variable names and file locations, and to understand their naming conventions, you will need to consult the dietary interview files on the 2003-2004 Examination Files page.
Food frequency variables and information about the variables are stored within the Questionnaire data files. To identify food frequency variable names and file locations, and to understand their naming conventions, you will need to consult the files on the 2003-2004 Questionnaire Files page.
Dietary supplement variables and information about the variables are stored within the Questionnaire data files. To identify dietary supplement variable names and file locations, and to understand their naming conventions, you will need to consult the files on the 2003-2004 Questionnaire Files page.
Sample weights are constructed for each 2-year survey cycle to account for over-sampling, survey non-response, and post-stratification. Because not all persons completed all portions of the survey, each individual in NHANES may be assigned multiple weight variables (see the Survey Orientation course for more information on how different sample weights are created). It is important to select the correct weight variable for your particular analysis and take extra care to include it in your analytic dataset.
National Center for Health
Statistics
3311 Toledo Road
Hyattsville, MD 20782
Phone: 1-866-441-NCHS (6247)
For data inquiries, use
nchsquery@cdc.gov
Problems or comments about the Tutorial?
Email the Tutorial Team:
NHANESWebTutorial@cdc.gov
Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA 30333, U.S.A
Tel: (404) 639-3311 / Public Inquiries: (404) 639-3534 / (800) 311-3435