search for: populationdensity

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2007 Jul 26
1
zeroinfl() or zicounts() error
I'm trying to fit a zero-inflated poisson model using zeroinfl() from the pscl library. It works fine for most models I try, but when I include either of 2 covariates, I get an error. When I include "PopulationDensity", I get this error: Error in solve.default (as.matrix(fit$hessian)) : system is computationally singular: reciprocal condition number = 1.91306e-34 When I include "BuildingArea", I get this error: Error in optim(fn = loglikfun, par = c(start$count, start$zero, if (dist == :...