On Sat, 21 Oct 2006, Gabriele Stocco wrote: > Dear R-help, > I am trying to make logistic regression analysis using the R function > "glm", with the parameter family set to binomial, in order to use a > logistic regression model. > I have 70 samples. The dependent variables has two levels (0 and 1) and > one of the independent variables has too two levels (0 and 1). > The variables associate in the way shown in the table: > > Dependent 0 1 > Independent 0 55 10 > > 1 0 5 > > This gives a strong association evaluated by the fisher test (p-value = > 0.0002481), but with the logistic regression it gives a p-value of 0.99 > with very high values of estimate and standard error (respectively and > -19.27 and 1769.26).
Please see the comment at the bottom of this message, as your claims are not supported by any code. > Is there any way (other function, different setting of a parameter) to > perform logistic regression analysis with these data with R? fit <- glm(matrix(c(55,0,10,5), 2, 2) ~ factor(c(0,1)), binomial()) fit0 <- glm(matrix(c(55,0,10,5), 2, 2) ~ 1, binomial()) anova(fit0, fit, test="Chisq") Resid. Df Resid. Dev Df Deviance P(>|Chi|) 1 1 16.929 2 0 2.208e-10 1 16.929 3.880e-05 is a reasonable way to do this. Beware the Hauck-Donner phenomenon (see e.g. MASS, the book) for t-tests of coefficients, although I do not get the values you quote. Since the expected values are low, you should not take the p value too seriously. > Thank you. > > Gabriele Stocco > University of Trieste > > ______________________________________________ > 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 > and provide commented, minimal, self-contained, reproducible code. > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ 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 and provide commented, minimal, self-contained, reproducible code.