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Multiple Imputation Using Gaussian Copulas
Missing observations are pervasive throughout empirical research, especially
in the social sciences. Despite multiple approaches to dealing adequately with
missing data, many scholars still fail to address this vital issue. In this
paper, we present a simple-to-use method for generating multiple imputations
using a Gaussian copula. The Gaussian copula for multiple imputation (Hoff,
2007) allows scholars to attain estimation results that have good coverage and
small bias. The use of copulas to model the dependence among variables will
enable researchers to construct valid joint distributions of the data, even
without knowledge of the actual underlying marginal distributions. Multiple
imputations are then generated by drawing observations from the resulting
posterior joint distribution and replacing the missing values. Using simulated
and observational data from published social science research, we compare
imputation via Gaussian copulas with two other widely used imputation methods:
MICE and Amelia II. Our results suggest that the Gaussian copula approach has a
slightly smaller bias, higher coverage rates, and narrower confidence intervals
compared to the other methods. This is especially true when the variables with
missing data are not normally distributed. These results, combined with
theoretical guarantees and ease-of-use suggest that the approach examined
provides an attractive alternative for applied researchers undertaking multiple
imputations
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