It seems to me that you are using polygon in a wrong way. What you probably need could be something like: polygon(c(rev(t$z), t$z), c(rep(0, nrow(t)), t$ht), col=2, border=NA) Stefano -----Messaggio originale----- Da: r-help-bounces at stat.math.ethz.ch [mailto:r-help-bounces at stat.math.ethz.ch]Per conto di LL Inviato: sabato 26 maggio 2007 12.34 A: r-help at stat.math.ethz.ch Oggetto: [R] polygon error? Hi.. I'm not sure why polygon returns an area above the standard normal curve. z <- pretty(c(-3,3), 100) ht <- dnorm(z) data <- data.frame(z=z, ht=ht) zc <- 1.645 plot(data, type="l") lines(data) t <- subset(data, z>zc) polygon(t, col="red") Thanks, Lance [[alternative HTML version deleted]] ______________________________________________ R-help at stat.math.ethz.ch 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.