Hi, The MatchIt manual recommends multiple imputation in section 5.2.5 on page 32. Is it possible to use multiple datasets generated by Amelia in MatchIt? Naming each dataset individually does not work (see Example 1 below). Similarly, the "data=list(...)" method of using multiple datasets in zelig does not work (see Example 2 below). Finally, I tried to create a new data frame called "allimputeddata.data" with the variables from each imputed dataset, but I receive an error message stating: Error in eval(expr, envir, enclos) : object "outcome" not found. I suspect I receive this message because the new data frame automatically renames the variables so that the outcome variables are now impute1.data.outcome, impute2.data.outcome, etc. Example 1: m.out <- matchit(outcome ~ var1 + var2 + var3, data=impute1.data, impute2.data, impute3.data, impute4.data, impute5.data, method = "nearest") Example 2: m.out <- matchit(outcome ~ var1 + var2 + var3, data=list(impute1.data, impute2.data, impute3.data, impute4.data, impute5.data), method = "nearest") Example 3: m.out <- matchit(outcome ~ var1 + var2 + var3, data=allimputeddata.data), method = "nearest") Thanks for your help. Jason Barabas <mailto:matchit@mail-1.hmdc.harvard.edu>