How to Download Data and Identify Supporting Documentation
Download SAS Transport Files
An NHANES analysis focusing solely on physical activity measurements will include SAS transport files from two data categories:
- Demographic Data
- Examination Data
- CVX – Cardiovascular Fitness Examination File
Demographic data are linked to the physical activity data by a common identifier, SEQN – the study participant’s identification number.
To build the “CVXMSTR” dataset for our sample SAS program, you will need to download demographic and cardiovascular fitness files from the 2001-2002 and 2003-2004 cycles. Remember that when creating a dataset for your own analysis, you need only download the data files relevant to that analysis.
From the NHANES homepage to the right: http://www.cdc.gov/nchs/nhanes.htm
- Click Questionnaires, Data Sets, and Related Documentation. From this page, click NHANES 2001-2002.
- Scroll down the page and click the Demographics link in the “Data, Documentation, Codebooks, SAS Code” section. Locate “Demographics Data, Docs, Questionnaire.” Right-click the Data link and select “Save Target As” to download and save the SAS transport file titled DEMO_B.
- Save the DEMO_B transport file to the C:\NHANES\DOWNLOAD directory created in Step 1.
Note that file names for NHANES data beginning in 2001 include a single letter suffix, used to indicate the 2-year cycle in which the data were collected.
|NHANES Data File Suffix||NHANES Cycle|
|A||1999 to 2000|
|B||2001 to 2002|
|C||2003 to 2004|
|D||2005 to 2006|
|E||2007 to 2008|
|F||2009 to 2010|
- Return to the NHANES 2001-2002 data page through the Questionnaires, Data Sets, and Related Documentation link located in the toolbar on the left.
- Scroll down the NHANES 2001-2002 page and click the Examination link in the “Data, Documentation, Codebooks, SAS Code” section. Scroll down to the “Cardiovascular Fitness” items and right-click the Data link to download the SAS transport file titled CVX_B by selecting “Save Target As”.
- Save the CVX_B transport file to the C:\NHANES\DOWNLOAD directory created in Step 1.
- Repeat steps 1 through 6 to download and save the demographic (DEMO) and cardiovascular fitness (CVX) files from the NHANES 2003-2004 cycle.
Bookmark the Data Documentation, Codebook, and Frequencies
Each NHANES dataset has accompanying documentation titled “Documentation, Codebook, and Frequencies” that you will need to refer to as you build your analytic dataset. This information is stored in an HTML file. To download the “Documentation, Codebook, and Frequencies” for CVX dataset:
- On the NHANES 2001-2002 Examination homepage, Right-click the Docs link located next to the CVX dataset. Choose “Save Target As” to download (not open) the “Documentation, Codebook, and Frequencies” to the C:\NHANES\DOWNLOAD folder.
- Repeat step 8 to download documentation from the NHANES 2003-2004 cycle for the CVX file.