Hi, I have make an analise with presence and absence, y=(1 e 0). I have a area continuous data and a sp data with 25 levels. I have 300 points. When I make glm((presenca/peso)~area,weights=peso,family=binomial,maxit=1000) where presenca is 0 or 1. peso is the unit = 1. area is the continuous data. The analysis is OK. When I put the sp and interactions in analysis this warning appear. glm((presenca/peso)~area*sp,weights=peso,family=binomial,maxit=1000) Warning message: fitted probabilities numerically 0 or 1 occurred in: (if (is.empty.model(mt)) glm.fit.null else glm.fit)(x = X, y = Y, Some ideas??? Thanks Ronaldo -- A person who has nothing looks at all there is and wants something. A person who has something looks at all there is and wants all the rest. -- | //|\\ [*****************************][*******************] || ( ? ? ) [Ronaldo Reis J?nior ][PentiumIII-600 ] | V [ESALQ/USP-Entomologia, CP-09 ][HD: 30 + 10 Gb ] || / l \ [13418-900 Piracicaba - SP ][RAM: 128 Mb ] | /(lin)\ [Fone: 19-429-4199 r.229 ][Video: SiS620-8Mb ] ||/(linux)\ [chrysopa at insecta.ufv.br ][Modem: Pctel-onboar] |/ (linux) \[ICQ#: 5692561 ][SO: CL 7.0 (2.2.19)] || ( x ) [*****************************][*******************] ||| _/ \_Powered by Gnu/Debian Woody D+:) | Lxuser#: 205366 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
On Fri, 20 Sep 2002, Ronaldo Reis Jr. wrote:> Hi, > I have make an analise with presence and absence, y=(1 e 0). > I have a area continuous data and a sp data with 25 levels. I have 300 points. > When I make > > glm((presenca/peso)~area,weights=peso,family=binomial,maxit=1000) > > where > > presenca is 0 or 1. > > peso is the unit = 1. > > area is the continuous data. > > The analysis is OK. > > When I put the sp and interactions in analysis this warning appear. > > glm((presenca/peso)~area*sp,weights=peso,family=binomial,maxit=1000) > > Warning message: > > fitted probabilities numerically 0 or 1 occurred > > in: (if (is.empty.model(mt)) glm.fit.null else > > glm.fit)(x = X, y = Y, > > Some ideas???When you fit logistic regression models to fairly sparse data you can often have a situation where for some combination of variables the response variable is either all 0 or all 1. In that case the maximum likelihood estimates for at least some of the coefficients will be infinite. That's what R is telling you. You should be able to tell which coefficients are infinite -- the coefficients and their standard errors will be large. When this happens the standard errors and the p-values reported by summary.glm() for those variables are useless. -thomas -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._