setx(z.out1, age = 20)

Hello, When I run a regression using as.factor to create indicator variables from categorical variables, the subsequent simulation steps using setx and sim do not work. When I run the regression where the indicator variables were created beforehand, the simulation steps work. So for example, I run z.out<-zelig(severe_anemic ~ net_status + anc_visit + as.factor(age) + as.factor(wealth) + as.factor(region), model = "logit", data = my.data) And then I run: x.out0<-setx(z.out, net_status = 0) x.out1<-setx(z.out, net_stutus = 1) s.out<-sim(z.out, x=x.out0, x1=x.out1, num=1000) After each of the preceding lines, I receive this error: Error in `contrasts<-`(`*tmp*`, value = "contr.treatment") : contrasts can be applied only to factors with 2 or more levels Thanks for any advice! Andrew Stokes Institute for Health Metrics and Evaluation