Hi Philippe, This is almost certainly the same issue with collinearity causing problems. Most of the time it is not nominals, but rather a series of variables that are linear transformations of each other (or quite close to being so). I would take a look at a correlation matrix of your dataset and see if there are any extremely high correlations (0.95 or greater) and see if removing those helps solve the problem. You might also try to add a ridge prior to the data by setting the =empri= argument in the =amelia()= function (see section 4.6.1 in the Amelia manual). Cheers, matt. ~~~~~~~~~~~ Matthew Blackwell Assistant Professor of Political Science University of Rochester url: http://www.mattblackwell.org On Fri, Sep 21, 2012 at 5:46 AM, Philippe Sulger &lt;philippe.sulger(a)econ.uzh.ch <mailto:philippe.sulger@econ.uzh.ch>> wrote: Dear Amelia users We are running impuations. In the model we are currently running we intentionally avoid to use ordinal-specifications. We have some specifications for nominal variables. We have successfully done multiple imputations with the same dataset specifying many ordinal variables and some more nominal variables. However, now we are running into the problem that for some reason we get for many single-imputation runs the error mentioned in the header of this email. Some runs seem to work fine (up to now). From https://lists.gking.harvard.edu/pipermail/amelia/2011-February/000547.html I see that this problem might be related to the specification of the nominals and collinearity among them in their "decomposed" nature. Note that we have "task 1 failed" and not "La.svd(x, nu, nv)" (followed by "error code 1..."). If this is still related to near-singularity problems, I have difficulties to understand why this happens now in a model where we have no ordinals and fewer nominals. Do you have a suggestion? Best, Philippe -- =============================================================== Philippe Sulger Visiting Scholar Institute of Criminology Sidgwick Avenue University of Cambridge CB3 9DA Cambridge, UK =============================================================== Email:philippe.sulger@econ.uzh.ch <mailto:philippe.sulger@econ.uzh.ch> ps596(a)cam.ac.uk <mailto:ps596@cam.ac.uk> Web:http://www.econ.uzh.ch/faculty/sulger.html http://www.crim.cam.ac.uk/people/visitors/philippe_sulger =============================================================== -- Amelia mailing list served by HUIT [Un]Subscribe/View Archive: http://lists.gking.harvard.edu/?info=amelia More info about Amelia: http://gking.harvard.edu/amelia Amelia mailing list Amelia(a)lists.gking.harvard.edu <mailto:Amelia@lists.gking.harvard.edu> https://lists.gking.harvard.edu/mailman/listinfo/amelia