I have the following binary data set: Sex Response 0 1 0 159 162 1 4 37 My commands library(MASS) sib.glm=glm(sib~sex,family=binomial,data=sib.data) summary(sib.glm) The coefficients in the output are Estimate Std. Error z value Pr(>|z|) (Intercept) -3.6826 0.5062 -7.274 3.48e-13 *** sex 2.2059 0.5380 4.100 4.13e-05 *** I have calculated the .95 confidencce interval for sex two ways: (1) confint(sib.glm) The result is 2.5 % 97.5 % (Intercept) -4.861153 -2.823206 sex 1.263976 3.428764
Using the usual confidence interval formula, (2) 2.2059 +/- 1.96*.538 = 1.15142. 3.26038 The results from (2) are identical to those from SPSS but do not agree with those from the confint function. I have reviewed the MASS pdf file and, seeing no solution there, have tried to get the Venables & Ripley book from the local college libraries but the only copies are out on loan. I suspect there is a simple explanation of the discrepancy, perhaps a modification to account for pre-asymptotic distribution. Or perhaps I misunderstand the application of the confint fuuction in the MASS package. If someone knows the explanation, I'd appreciate it. -- Jerome L. Myers [[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.