K. Fleischer wrote:
Dear all,
I have built glm models based on presences/absences and a number of
predictor maps and would like to compute habitat suitability based on
the modelled coefficients.
I thought this is pretty straight forward and wanted to use predict()
and supply the new data in a data frame, with one column for each
predictor.
However, I do get an error msg warning me that the number of rows for
old and new data do not match.
the script looks like that:
model<-glm(species~temp+prec+elev,family=binomial(link=logit))
#whereby temp,prec,elev are in vector format and contain the elements
on species presence/absence; species is vector of 0's and 1's
(length=319)
wholearea<-data.frame(cbind(as.vector(temperature),as.vector
(precipitation),as.vector(elevation)) # (length=7526)
predict(model, newdata=wholearea,type="response")
Warning message: 'newdata' had 7526 rows but variable(s) found have
319 rows.
Ive searched quite a while for the answer now, has anyone encountered
that problem before?? thanx in advance.
Your newdata does not contain the variables named temp, prec, and elev
that your model refers to. (And you should get rid of that cbind, but
that is not the problem.)
--
O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
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