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Dear R-Help, I am trying to perform forward selection on the following coxph model: >my.bpfs <- Surv(bcox$pfsdays, bcox$pfscensor) > b.cox <- coxph(my.bpfs ~ Cbase + Abase + Cbave + CbSD + KPS + gender + as.factor(eor) + Age)>stepAIC(b.cox, scope=list(upper =~ Cbase + Abase + Cbave + CbSD + KPS + gender + as.factor(eor) + Age, lower=~1), direction= c("forward")) However

Dear R-help, I am trying to perform residual diagnostics on a repeated measures mixed effect model. With 3 time points as the fixed effect and subjects as the random effects. > time.linearc<- summary(lmer(cnim~(as.factor(time)), random= ~1|subj, data=ex.rmc, na.action=na.omit)) > time.linearc When I perform : >res <- residuals(time.linearc) I receive the following error