31 Exploring strategies for multiple imputation of multicategory variable

Oregon Convention Center 

Multiple imputation (MI) of a variable with multiple categories can be accomplished in several ways. In the Influenza Hospitalization Surveillance Network, influenza type/subtype is a multicategory variable subject to missingness. MI of this variable presents challenges: influenza type/subtype variable is derived from two categorical variables, only one of which has missing data.; additionally, surveillance data are collected by stratified sampling. Imputing influenza type/subtype using a principled method, while accounting for sampling design and achieving compatibility between the MI and the analysis models can be challenging. We explored strategies for imputing missing data for this variable. We used a simulation study to compare the performance of the selected approaches. Although the proportion of observations with missing subtype was high, the missing mechanism was likely missing at random (MAR); thus, we evaluated the benefits of using MI compared to a complete case analysis.

Multiple imputation

multicategory variables 

Section on Statistics in Epidemiology