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Supplementary Resources for National Health Interview Survey Public Use Files With Variance Estimation Singleton PSUs - 2003, 2005, 2007

The public use file variance estimation structure for the 1997-present National Health Interview Survey (NHIS) almost always provides 2 variance estimation primary sampling units (PSU) for each variance estimation stratum.  This page provides supplementary resources for the small number of occurrences of singleton PSUs in the 1997-present NHIS public use files.

Singleton PSUs occur in the following public use files:

 2003 Sample Child File (1 singleton PSU)

 2005 Sample Child File (2)

 2007 Sample Child File, 2007 Child Alternative Medicine File (2)

Some complex sample design software packages (e.g., SUDAAN, Stata 10, R (including the Survey add-on package)) have options available to compute appropriate variance estimates when singleton PSUs are present.  Other complex sample design software packages (e.g., SPSS, Stata 9, SAS survey procedures) do not compute appropriate variance estimates when singleton PSUs are present.

NCHS has created supplemental files to enable users to compute appropriate variance estimates with all contemporary complex sample design packages.  It is not necessary to use these supplemental files with SUDAAN, Stata 10, or R, but the files can be used if a user chooses to do so.  Stata 9 will generate missing values for standard error estimates if the supplemental files are not used, and SPSS and the SAS survey procedures will produce standard error estimates that are slightly smaller than they should be if the supplemental files are not used.

2003 Sample Child File:

 Supplemental file is available here.

 Technical guidance is available here.

2005 Sample Child File:

 Supplemental file is available here.

 Technical guidance is available here.

2007 Sample Child File, 2007 Child Alternative Medicine File:

 Supplemental files are available here.

 Technical guidance is available here.

 

This page last reviewed November 20, 2008

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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Centers for Disease Control and Prevention
National Center for Health Statistics
Hyattsville, MD
20782

1-800-232-4636