On 16-Mar-07 11:56:56, Alberto Monteiro wrote: > I have a question, maybe it's better to explain by example: > > alpha <- 0.3 > beta <- 0.4 > sigma <- 0.5 > err <- rnorm(100) > err[15] <- 5; err[25] <- -4; err[50] <- 10 > x <- 1:100 > y <- alpha + beta * x + sigma * err > ll <- lm(y ~ x) > plot(ll) > > Now, the graphs clearly show that 15, 25 and 50 are the indexes > of the bad points. How can I retrieve this information from ll? > > Alberto Monteiro
ll is the output of a linear model fiited by lm(), and so has several components (see ?lm in the section "Value"), one of which is "residuals" (which can be abbreviated to "res"). So, in the case of your example, which(abs(ll$res)>2) 15 25 50 extracts the information you want (and the ">2" was inspired by looking at the "residuals" plot from your "plot(ll)"). Best wishes, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <[EMAIL PROTECTED]> Fax-to-email: +44 (0)870 094 0861 Date: 16-Mar-07 Time: 12:19:02 ------------------------------ XFMail ------------------------------ ______________________________________________ [email protected] 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.
