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Hello, Why the correlation between the random effects is negative? library(coxme) rats1 <- coxme(Surv(time, status) ~ (1|litter), rats) random.effects(rats1)[[1]] #one value for each of the 50 litters print(rats1) rats2 <- lmekin(time ~ (1|litter), rats) fixed.effects(rats2) random.effects(rats2)[[1]] #one value for each of the 50 litters print(rats2) cor(random.effects(rats1)[[1]],random.effects(rats2)[[1]]) Thanks [[alternative HTML version deleted]]

...estion on fitting data by coxme. In particular I want to fit a random intercept and random slope cox model. Using the rats dataset as an example, I generated another covariate x2 and want to specify a random slope for x2. Here is my code: x2=matrix(rep(runif(50), 3), 50, 3) x2=as.vector(t(x2)) rats2=cbind(rats, x2) But when I used the coxme function as follows, it gave an error message. What is the right way to do it? Thanks a lot! coxme(Surv(time, status) ~ rx+x2, data=rats2, random=~ (1+x2)|litter ) Lei Liu Assistant Professor Division of Biostatistics and Epidemiology Dept. of Public...

...22 at medschl.cam.ac.uk Cc: R-help at stat.mat.ethz.ch, liulei at virginia.edu, spencer.graves at pdf.com Content-MD5: BXKVsHtW/1I9mIUqrXBU0g== The original question involved a strange error message from coxme when trying to fit a random slopes model: coxme(Surv(time, status) ~ rx+x2, data=rats2, random=~ (1+x2)|litter) Synopsis a. coxme does not yet support random slopes models b. it should recognize the request and print a sensible error, instead it just dies further down in the routine after it has gotton thoroughly confused. c. the actual error message is intere...