Hi Matt, Dear all, just to clarify: The issue is not related to risk-ratios, I ran a simple "ls" model, the simulated ev are just not stored in the same structure as they used to in older versions: as a list at sim.out$qi[[1]] instead of as a data vector at sim.out$qi$ev. (which prohibits to run older scripts and is pretty tiresome). Simulating multiple vectors - well take a look at it, here for logit. I'm running Zelig_4.1-0/. //library(Zelig)// //data(turnout)// //z.out <- zelig(vote ~ age + race, model = "logit", data = turnout) ////x.out <- setx(z.out, age = 30)// //s.out <- sim(z.out, x = x.out)// //s.out$qi$ev # old syntax - straight from the manual: NULL// //names(s.out$qi) s.out$qi[[1]] # ev are here now //// //x2 <- setx(z.out, age=10:20)// //s2.out <- sim(z.out, x2)// //s2.out$qi$ev #NULL s2.out$qi[[1]] # NULL (!) //s2.out[[1]]$qi[[1]]//# age=10 covariates, ev// //s2.out[[2]]$qi[[1]]//# age=11 covariates, ev// //.../ Please tell me if I can be of further assistance. Best Steffen On 11/13/2012 10:10 PM, Matt Owen wrote: