I don't see the problem with the following... the citations and baseball data work fine, but my simulated data seems to give BTm a headache. What am I missing? --- library(BradleyTerry) library(doBy) ng <- 100 players <- factor( sort( c( "jeff", "mike", "paul", "rich" ) ) ) np <- length( players ) p1 <- factor( c( rep( "jeff", ng ) , rep( levels( players ), np ) ) , levels=players ) p2 <- factor( c( rep( "mike", ng ) , rep( levels( players ), each=np ) ) , levels=players ) p1s <- c( rnorm( n=ng, mean=-0.5, sd=2 ), rep( 1, np^2 ) ) p2s <- c( rnorm( n=ng, mean=0.5, sd=2 ), rep( 0, np^2 ) ) results <- data.frame( winner=factor( levels(players)[ ifelse(p1s<p2s,p2,p1)], levels=players ) , loser=factor( levels(players)[ ifelse(p1s<p2s,p1,p2) ], levels=players) , Freq=c( rep( 1, ng ), rep( 1, np^2) ) ) results <- summaryBy(Freq ~ winner + loser, data=results, FUN=c(sum) ) attr(results, "names") <- c( "winner", "loser", "Freq" ) results.btm <- BTm( results ~ .. ) # this spits out an error: ---- Error in BTm(results ~ ..) : subscript out of bounds > sessionInfo() R version 2.0.1, 2004-11-15, i386-pc-linux-gnu attached base packages: [1] "methods" "stats" "graphics" "grDevices" "utils" "datasets" [7] "base" other attached packages: BradleyTerry brlr doBy Hmisc "0.8-5" "0.8-8" "1.6" "3.0-1" I have also tried this on Windows XP with R version 2.3.1 with same result. -- --------------------------------------------------------------------------- Jeff Newmiller The ..... ..... Go Live... DCN:<jdnewmil at dcn.davis.ca.us> Basics: ##.#. ##.#. Live Go... Live: OO#.. Dead: OO#.. Playing Research Engineer (Solar/Batteries O.O#. #.O#. with /Software/Embedded Controllers) .OO#. .OO#. rocks...1k