Keep & Merge Data

Purpose

To conduct analyses using NHANES I data, an analyst will typically include selected variables from at least two data files. Therefore, you will need to keep and merge data to create your analytic dataset to include variables from different data files.

Task 1: Keep NHANES I Data

NHANES I data files were released by their collection method or component. Many of these are very large data files with many variables.  Most analysts will only need a few selected variables.  You will likely wish to keep only those variables when you create your analytic dataset. This process uses a SAS option statement called keep.

• Key Concepts about Keeping Data in NHANES I
• How to Keep NHANES I Data
• Download Sample Code and Dataset

Task 2: Merge NHANES I Data

The NHANES I data files were organized primarily by 20 different topic areas. It is very likely that variables of interest to you come from different data components (topic areas).  Joining the components of the data files is called merging.

When choosing which files to merge, be aware that some of these files only contain data on the detailed subsample or the augmented population.

• Key Concepts about  Merging Data in NHANES I
• How to Merge NHANES I Data
• Download Sample Code and Dataset

NHANES I Tutorial Home

Survey Orientation

Preparing an Analytic Dataset

Survey Design Factors

Additional Resources

National Center for Health Statistics
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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

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