Please folks ... On Wed, Feb 29, 2012 at 7:14 AM, Michael <comtech....@gmail.com> wrote: > How did you see it's non-significant?
You need to take or review a basic statistics course. Pr(>|Z|) is your P value. > > Thanks! > > On Wed, Feb 29, 2012 at 9:10 AM, Sarah Goslee <sarah.gos...@gmail.com>wrote: > >> On Wed, Feb 29, 2012 at 10:02 AM, Michael <comtech....@gmail.com> wrote: >> > Hi all, >> > >> > As you can see from below, the result is strange... >> >> Not really. >> >> > I would imagined that the bb result should be much higher and close to 1, >> > any way to improve the fit? >> > >> > Any other classification methods? >> > >> > Thank you! >> > >> > data=data.frame(y=rep(c(0, 1), times=100), x=1:200) >> > aa=glm(y~x, data=data, family=binomial(link="logit")) >> > >> > newdata=data.frame(x=6, y=100) >> > bb=predict(aa, newdata=newdata, type="response") >> > bb >> > >> > >> >> bb >> > >> > 1 >> > >> > 0.4929125 >> >> >> What did you expect? Your model is completely nonsignificant; there's no >> way to predict y from x, If this statement is to be parsed as "non-significant --> no prediction", then this statement is false. The size of P values need have nothing to do with the quality of a fitted model's predictions. Cheers, Bert and that's what your predicted value tells you. >> >> > summary(aa) >> >> Call: >> glm(formula = y ~ x, family = binomial(link = "logit"), data = data) >> >> Deviance Residuals: >> Min 1Q Median 3Q Max >> -1.190 -1.177 0.000 1.177 1.190 >> >> Coefficients: >> Estimate Std. Error z value Pr(>|z|) >> (Intercept) -0.030152 0.283924 -0.106 0.915 >> x 0.000300 0.002450 0.122 0.903 >> >> (Dispersion parameter for binomial family taken to be 1) >> >> Null deviance: 277.26 on 199 degrees of freedom >> Residual deviance: 277.24 on 198 degrees of freedom >> AIC: 281.24 >> >> Number of Fisher Scoring iterations: 3 >> >> >> I can only assume that you didn't construct the data frame that >> you intended to test. >> >> -- >> Sarah Goslee >> http://www.functionaldiversity.org >> > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
