KEYWORDS:
Sample Design, Estimation Procedures, Public-Use Data Files

BACKGROUND:
The National Immunization Survey( NIS) measures and monitors vaccination coverage rates among children aged 19-35 months in the U.S., the 50 states and 28 urban areas

OBJECTIVE(S):
To present an overview of the NIS sample design and estimation procedures, and to discuss how to analyze the NIS public-use data files.

METHOD(S):
The NIS consists of a quarterly stratified random-digit-dialing telephone survey of the parents/guardians of children aged 19-35 months, followed by a mail survey of the children's providers. The provider-reported immunization histories are used to produce estimates of vaccination coverage using estimation methods designed to reduce nonresponse bias and bias resulting from the exclusion on nontelephone households. Recently, we released annual public-use data files for 1995-2001. The public-use files contain selected data from the telephone survey and provider data collection. They can be used to calculate annual estimates of vaccination coverage for IAP areas, states, and demographic and socioeconomic subdomains of the population.

RESULT(S):
The NIS Data User’s Guides, the NIS Code Book, and other accompanying documents provide a great deal of information to assist data users in understanding the NIS and analyzing the public-use data files.

CONCLUSIONS(S):
The NIS uses sampling and estimation procedures that result in comparable estimates of vaccination coverage across all 50 states and 28 urban areas. Seven annual public-use data files are currently available for analysis purposes.

LEARNING OBJECTIVES:
To provide an overview of the NIS sampling and estimation procedures and illustrate how to analyze the public-use file data.