Sorry, I thought the link would work for people because it is a public link and it works for me when I run it in R. Anyways, here is an example set of data that I am having trouble with:
/id <- c(230017,230017,230017,230018,230018,230018,230019,230019,230019,230020,230020, 230020,230021,230021,230021,230022,230022,230022,230023,230023,230023,230024, 230024,230024,230025,230025,230025,230026,230026,230026) age <- rep(c(30,36,42),10) outcome <- c(12,17,10,5,5,2,NA,NA,NA,8,6,5,11,13,10,15,11,15,13,NA,9,0,0,0,20, 14,16,1,2,2) mydata <- as.data.frame(cbind(id,age,outcome)) fit <- by(mydata, mydata$id, function(x) fitted.values(lm(outcome ~ age, data=x))) fit1 <- unlist(fit) names(fit1) <- NULL interaction.plot(mydata$age, mydata$id, fit1,legend=F)/ Note that the following works fine: /lm(outcome ~ age, data=mydata)/ Any help would be greatly appreciated. Thanks! -- View this message in context: http://r.789695.n4.nabble.com/Problem-with-by-statement-for-spaghetti-plots-tp3788536p3797025.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.