Purpose
Variables and the information about the variables is stored in various types of data and documentation files. You need to know what information is in these files and how to access them to prepare for your analysis. You use this documentation to decide which variables to include in your analysis, identify the variable names and file locations, and consult the data file documentation for detailed data processing and analytic information.
Task 1: Decide which variables to include
Your analysis will require a subset of the variables available in NHANES. To decide which variables are needed in your analysis, you need to review the survey documentation.
- Key Concepts about Deciding Which NHANES Variables to Include
- How to Decide Which NHANES Variables to Include
Task 2: Identify variable names and file locations
Variables are stored in different components. Use the variable list of each component to identify the variable names and file locations.
- Key Concepts about Identifying Variable Names and File Locations
- How to Identify Variable Names and File Locations
Task 3: Consult the documentation
Before analyzing the data, you will need to know how the variable is coded, data editing, processing, and collection information, and the frequency (or sample size) of the variable. This information is found in the documentation.
IMPORTANT NOTE You cannot determine whether a variable is appropriate to use in your analysis without consulting the data file documentation. Variables may have similar names, be auxiliary, or used for excluding sample persons from certain measures. Read the documentation.
Contact Us:
- National Center for Health Statistics
3311 Toledo Rd
Hyattsville, MD 20782 - 1 (800) 232-4636
- cdcinfo@cdc.gov
