1. Integrated Health Interview Series (IHIS): Providing Free, Integrated NHIS Data over the Internet Miriam L. King, PhD, Minnesota Population Center Brian R. Lee, MPH, PhD, Minnesota Population Center Andrew Ward, MPH, PhD, Kansas Health Institute

2. Presenter Disclosures
Miriam L. King
Brian R. Lee
Andrew Ward
The following personal financial relationships with commercial interests relevant to this presentation existed during the past 12 months:
No Relationships to Disclose

3. NHIS Strengths Large (60-100k) nationally representative survey
Covers health status, behaviors, care
Consistent core content, periodic special topics
Primary source for tracking progress toward public health goals (e.g.,Healthy People)
Suitable for studying health disparities
Microdata for 1963-present, PUMS available covering 4 million persons

4. NHIS PUMS rarely used for multi-year analysis
Based on sample from PubMed (1978 forward)
70% use 1 year
10 % use 2 years
20% use 3+ years
4 % used data before and after survey redesign in 1997
DESPITE consistency in subject content

5. NHIS PUMS problems No. files (500+) No. variables (40,000+)
Overwhelming documentation (1000’s pages/yr)
Subtle changes (coding schemes, variable names and source files, question wording, universes)
Sample design changes
NCHS forward-looking, not emphasis on consistency (esp. before 1997)

6. IHIS Solutions Link and reformat files into 1 per year
Create 14,000 consistently-coded variables (7000 now public)
Create on-line variable-specific documentation
Document subtle changes (universe, linked survey text, weights)
Impose consistent codes w/out info loss
Data extract engine merges files, creates extract w. only years and variables needed

10. Methods Support from NICHD (in year 7 of 10) Customized programming
System driven by machine understandable metadata (e.g., data dictionaries, variable transformation tables, control files)
Humans work in Excel and Word files, saved as XML files read by computers
Data recoded via Ruby program w. data stored in relational database

11. Builds upon other MPC data projects
Over 50,000 registered users worldwide:
US census microdata ( , IPUMS)
American Community Survey (2000 forward)
Census samples from 50+ countries (1960s forward)
U.S. Current Population Survey (1962 forward)
County-level aggregate U.S. census data,
American Time Use Survey (2003 forward)

12. IHIS goals Document, make public 7000 remaining integrated variables
Add on-line tabulator, family pointers, other features
Make IHIS better known (1,000 users now; 75% use multiple years’ data)
Encourage classroom use

13. To Learn More IHIS website: www.ihis.us
MPC data website:
NHIS website:
Pick up brochures
Visit MPC exhibit for demonstration