Gaining Acceptance for the Use of Multiple Imputation in the

Analysis of Public Data

Traffic Records ForumJuly 14, 2003

Ted DonnellyRI Department of Health

Do I look like a salesman?

Do I look like a salesman?

• Career in public service

Do I look like a salesman?

• Career in public service

• Skill set is technical

Do I look like a salesman?

• What is my product?

Do I look like a salesman?

• What is my product?

• Who are my customers?

Meteorology

• Rainfall

• Wind resources

• Application to GIS layer

Chandra X-ray of the Crab Nebula

Departments of AstroPhysics and Statistics

Harvard University

Wildfires in the American West

Oak Ridge National Laboratory

Important government applications where imputation is used

• US Census 2000• Survey of Income and Program Participation

(Census Bureau)• Behavioral Risk Factor Surveillance System

(CDC)• Fatality Analysis Reporting System (NHTSA)• Crash Outcome Data Evaluation System

(NHTSA)

Winners and Losers

• Utah vs. Evans II

• Additional House seat was assigned to NC

• Use of imputation to improve population estimates upheld by U.S. Supreme Court

Do I look like a salesman?

• Who are my customers?

Customers

• Demographers and epidemiologists familiar with Census Bureau methods

Customers

• Physical scientists use these techniques routinely in graphic representations

Customers

• Survey researchers find MI useful in analysis of incomplete surveys and to calculate improved sample weights

Customers

• State legislators

• Data Managers

• Governor’s Highway Safety Representative

State legislators

• part-time elected representatives

• educated and politically astute

• familiar with the results of survey research, especially opinion polls

Pew Research Center

“Based on the total sample, one can say with 95% confidence that the error attributable to sampling and other random effects is plus or minus 3.5 percentage points.”

Data managers

• Develop system for purposes that use storage and retrieval

• May have sophisticated skills but little experience with research

• Primarily concerned with integrity and usefulness of the data

Governor’s Highway Safety Representative

• Bring HSR along with use of MI in FARS and CODES

• Technical staff may be familiar with MI

• Be available for follow-up consultation

Additional Concern: Changing public data sets

• multiple imputation is not a method for changing data

• tool for improving estimates in the analyses that make data meaningful and error estimable