I don't understand the following behavior of ccf library(ts) a<-runif(100) b<-runif(100) acf(a) # works ccf(a,b) # fails #.. because of the following ts.union(a,b) # which fails on tsp(x) in .cbind.ts #tsser <- sapply(sers, function(x) length(tsp(x)) > 0) (R 1.6.1, Windows) Dieter Menne