[R] Error message in polr

From: <german.lopez_at_ua.es>
Date: Sun 13 Nov 2005 - 08:17:52 EST

Dear members of the list,
  I'm fitting ordinal regressions using polr, and in some models I get the error copied below. Dependent variable is an ordered factor of bird abundance categories, and predictors are continuous habitat variables.

> ro6 <- polr(formula = abun ~ InOmbrot + Oliva.OC + ToCultAr +
DivCulArb + AltitMax + COORXY)
> summary(ro6)

Re-fitting to get Hessian

Error in La.svd(x, nu, nv, method) : error code 8 from Lapack routine dgesdd
In addition: Warning messages:
1: NaNs produced in: dlogis(x, location, scale, log) 2: NaNs produced in: dlogis(x, location, scale, log)

But if I call for the "ro6" object I get the coefficients but without standard errors:

> ro6

polr(formula = abun ~ InOmbrot + Oliva.OC + ToCultAr + DivCulArb +

    AltitMax + COORXY)


     InOmbrot Oliva.OC ToCultAr DivCulArb AltitMax
-2.721242e-01 2.590153e-02 2.098157e-02 7.908437e-01 2.088895e- 03



     0|1 1|2 2|3
18.16425 18.97070 20.94103

Residual Deviance: 817.667
AIC: 835.667 It seems that the error is related to the number of predictors involved since if I use a lower number, say five predictors, polr does not produce this error message in summary. I have been looking at previous messages concerning errors in polr but I haven't found the solution. I would ackowledge very much any help.

  Germán López

R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sun Nov 13 08:27:12 2005

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