To push the point a bit further, Vito, if you allow just a bit variation in the data by changing one of the y=1 cases to 0 or one of the y=0 cases to 1, then you'll be able to fit the glm model. If these are real-world data and if you still want to describe them, then a deterministic statement
y=1 if x>a y=0 if x<=a where a can be any value between 29 and 33 would work because there is no uncertainty in the model (other than the exact location of a). Tim ---- Original message ---- >Date: Fri, 28 Jan 2005 09:55:53 -0500 >From: "Charles Annis, P.E." <[EMAIL PROTECTED]> >Subject: RE: [R] GLM fitting >To: "'Vito Ricci'" <[EMAIL PROTECTED]>, <[email protected]> > >Vito: > >Please plot your data: > >y <- c(1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0) >x <- c(37, 35, 33, 40, 45, 41, 42, 20, 21, 25, 27, 29, 18) >plot(x, y) > >You will see that ANY step function between 29 < x < 33 will describe these >observations perfectly. > > >Charles Annis, P.E. > >[EMAIL PROTECTED] >phone: 561-352-9699 >eFax: 614-455-3265 >http://www.StatisticalEngineering.com > >-----Original Message----- >From: [EMAIL PROTECTED] >[mailto:[EMAIL PROTECTED] On Behalf Of Vito Ricci >Sent: Friday, January 28, 2005 5:14 AM >To: [email protected] >Subject: [R] GLM fitting > >DeaR R-useRs, > >I'm trying to fit a logist model with these data: > >> dati > y x >1 1 37 >2 1 35 >3 1 33 >4 1 40 >5 1 45 >6 1 41 >7 1 42 >8 0 20 >9 0 21 >10 0 25 >11 0 27 >12 0 29 >13 0 18 > >I use glm(), having this output: > >> g<-glm(y~x,family=binomial,data=dati) >Warning messages: >1: Algorithm did not converge in: glm.fit(x = X, y = >Y, weights = weights, start = start, etastart = >etastart, >2: fitted probabilities numerically 0 or 1 occurred >in: glm.fit(x = X, y = Y, weights = weights, start = >start, etastart = etastart, >> g > >Call: glm(formula = y ~ x, family = binomial, data = >dati) > >Coefficients: >(Intercept) x > -348.23 11.23 > >Degrees of Freedom: 12 Total (i.e. Null); 11 Residual >Null Deviance: 17.94 >Residual Deviance: 7.011e-10 AIC: 4 > >I don't understand the meaning of warning. Can anyone >help me? Many thanks. >Cheers, >Vito > > >===== >Diventare costruttori di soluzioni >Became solutions' constructors > >"The business of the statistician is to catalyze >the scientific learning process." >George E. P. Box > >Top 10 reasons to become a Statistician > > 1. Deviation is considered normal > 2. We feel complete and sufficient > 3. We are 'mean' lovers > 4. Statisticians do it discretely and continuously > 5. We are right 95% of the time > 6. We can legally comment on someone's posterior distribution > 7. We may not be normal, but we are transformable > 8. We never have to say we are certain > 9. We are honestly significantly different > 10. No one wants our jobs > > >Visitate il portale http://www.modugno.it/ >e in particolare la sezione su Palese >http://www.modugno.it/archivio/palese/ > >______________________________________________ >[email protected] mailing list >https://stat.ethz.ch/mailman/listinfo/r-help >PLEASE do read the posting guide! >http://www.R-project.org/posting-guide.html > >______________________________________________ >[email protected] mailing list >https://stat.ethz.ch/mailman/listinfo/r-help >PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
