How does IHIS add value to NHIS data?
IHIS includes many variable features not available for the original NHIS public use files. By using the IHIS data extraction system, analysts can select the years and variables they are interested in and work with a single dataset, without having to link or combine multiple files. IHIS provides online documentation that describes variable meaning and addresses comparability issues, along with providing information about years available, universes, codes and frequencies, question wording, appropriate weights, and source files for each included variable. The online tabulator allows experienced researchers to produce results quickly and allows new researchers to answer questions and create tables without downloading data or using a statistical package.
The large number of topics covered by the NHIS make it difficult for researchers to determine from the public use files which variables are available across time. Changes in variable names, even when the question wording remained the same, pose a further challenge. IHIS provides consistent variable names and displays which variables are available, by year and topic, in a user-friendly display on its website. Once researchers identify the years and variables relevant to their research project, they can create a data extract or analyze online the variables they choose.