Hi David, My apologies, I am not sure if this makes a big difference in your assessment of the problem, but the results I just sent were only from a portion (1/15) of the data. The dataset is rather large and the computer I am currently using to set up the models is limited in its capabilities to analyze large datasets. When I run the code you provided on a larger portion of the data (1/2) this is the output I receive: LCOVER LOCS 1 2 3 4 5 6 7 9 0 1692196 630659 550623 6140352 180896 255512 785929 63756 1 141 30 48 279 9 14 36 1 2 17 4 5 14 3 3 4 1 3 0 0 0 3 0 0 1 0 5 2 0 0 0 0 0 0 0 Thanks again for your time and assistance, Nate Nathan Svoboda Graduate Research Assistant Mississippi State University ________________________________
From: David Winsemius [mailto:dwinsem...@comcast.net] Sent: Thu 5/24/2012 1:54 PM To: Nathan Svoboda Cc: r-help@r-project.org Subject: Re: [R] R Error: System is computationally singular On May 24, 2012, at 1:57 PM, Nathan Svoboda wrote: > Greetings, > > I am trying to fit a zero-inflated Poisson model using zeroinfl() > from the > pscl library. I have 5 covariates (4 continuous, 1 categorical); the > categorical variable has 7 levels. I have had success fitting > models that > contain only the continuous covariates; however, when I add the > categorical > variable to any of the models (or if I run it by itself) I get the > following > error: > > Error in solve.default(as.matrix(fit$hessian)) : > > system is computationally singular: reciprocal condition number = > 3.46934e-20 > > The code I am using is: > > library(pscl) > f1 <- formula(LOCS ~ as.factor(LCOVER) + D_ROADS + D_WATER + D_EDGE + > D_GRASS) > ZIP1 <- zeroinfl(f1, dist="poisson", link = "logit", data = FAWNS) > > There is no correlation between my covariates. Also, I tried > reducing my > categorical covariate to 3 levels and still receive the same error. > Can > anyone suggest why I may be getting this error when I add the > categorical > covariate? > What does this show: with( FAWNS, table(LOCS, LCOVER) ) -- David Winsemius, MD West Hartford, CT [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
