Hello, I am running several regressions with multiply imputed data sets, and Zelig is unable to provide the summary of the regression results when I run a multilevel model (this happens with any multilevel model supported by ZeligMultilevel). A reproducible example is the following: *require(Amelia)* *require(Zelig)* *require(ZeligMultilevel)* *data(freetrade)* *amelia.ft <- amelia(freetrade, ts="year", cs="country")* *# Non-multilevel model* *z.out1 <- zelig(tariff ~ pop + country, data=amelia.ft, model="ls")* *# summary() works fine* *summary(z.out1)* *# Multilevel model* *z.out2 <- zelig(tariff ~ pop + tag(1 | country), data=amelia.ft, * * model="ls.mixed")* *# summary() does not work* *summary(z.out2)* The error message is: *Error in object[[1]]$result$call : $ operator not defined for this S4 class* The same issue is described here<http://stackoverflow.com/questions/16571580/multi-level-regression-…-l>, where a solution is also provided in the form of a slightly modified version of summary.MI(). The problem is that once the modified version of summary.MI() has been loaded, the function no longer works with standard models. Is there a better workaround? Thank you in advance, Mattia -- Mattia Guidi, Ph.D Post-doctoral Fellow LUISS Guido Carli Department of Political Science & School of Government Via di Villa Emiliani 14 00197 Rome (Italy) Tel: +39 06 8522 5706