Hi there, Usually this error means one of two things: 1) There are linearly dependent or extremely highly correlated variables in your dataset. 2) The imputation model isn't identified because you have more parameters than observations. Note that you need far more observations than in a typical regression because you need to run regressions for each column with missing data. Note that you have turned off the internal Amelia error checking, which should give you an informative error message if there is an obvious problem with the data. Use "incheck = TRUE" to get that. Either way, you should probably start with a couple of variable to see if Amelia runs then and then try to remove any highly correlated (rho > 0.95 or so) variables from the data. You can also use the "empri" argument to stabilize the computation. See the manual for more details on this. Cheers, Matt

~~~~~~~~~~~ Matthew Blackwell Assistant Professor of Government Harvard University url: <http://www.mattblackwell.org>http://www.mattblackwell.org On Mon, Nov 9, 2015 at 12:31 AM W. D. <<mailto:WD@a7h.com>WD@a7h.com> wrote: Hi, I ran something similar to:   DataImputed <- amelia(x=GroupData,incheck=FALSE) GroupData is several thousand observations with about 4 dozen variables. After iterating over a thousand times with this error:   error: inv_sympd(): matrix appears to be singular It ended with:   Error in emarch(x.stacked$x, p2s = p2s, thetaold = NULL,   tolerance = tolerance, :   BLAS/LAPACK routine 'DLASCL' gave error code -4 I searched online for both of these error messages but didn't find anything useful. Do you have any idea what might be going on, or how to fix it? Thanks for any light you can shed! -- Amelia mailing list served by HUIT [Un]Subscribe/View Archive: <http://lists.gking.harvard.edu/?info=amelia>http://lists.gking.harvard.edu/?info=amelia More info about Amelia: <http://gking.harvard.edu/amelia>http://gking.harvard.edu/amelia Amelia mailing list <mailto:Amelia@lists.gking.harvard.edu>Amelia@lists.gking.harvard.edu To unsubscribe from this list or get other information: <https://lists.gking.harvard.edu/mailman/listinfo/amelia>https://lists.gking.harvard.edu/mailman/listinfo/amelia