tumor.lst<-scan(what=list(dose=0,time=0,y=0)) 0 11 0 0 104 0 300 8 0 300 104 1 600 11 0 600 104 1 I other data omitted for space considerations I tumor.df<-data.frame(tumor.lst) tumor.fit<-glm(y~dose+time, family=binomial(link=logit),data=tumor.df) summary(tumor.fit) Deviance Residuals: Min 1Q Median 3Q Max -1.097395 -0.8206817 -0.5886815 -0.06352017 2.348401 Coefficients: Value Std. Error t value (Intercept) -7.400518981 2.8509479454 -2.595810 dose 0.002413828 0.0008839569 2.730708 time 0.055395038 0.0277976033 1.992799 Residual Deviance: 137.8663 on 147 degrees of freedom anova(tumor.fit,test="Chisq") Analysis of Deviance Table Binomial model Response: y Terms added sequentially (first to last) Df Deviance Resid. Df Resid. Dev Pr(Chi) NULL 149 160.5651 dose 1 7.05758 148 153.5076 0.007893063 time 1 15.64132 147 137.8663 0.000076563 tumor.fit2<-glm(y~time+dose,family=binomial(link=logit), data=tumor.df) anova(tumor.fit2,test="Chisq") .i(.Analysis of deviance table:in S-plus anova; Analysis of Deviance Table Binomial model Response: y Terms added sequentially (first to last) Df Deviance Resid. Df Resid. Dev Pr(Chi) NULL 149 160.5651 time 1 14.66734 148 145.8978 0.000128249 dose 1 8.03156 147 137.8663 0.004596931