On 18-Dec-2012 20:09:36 Beatriz González Domínguez wrote: > Hello, > > I have done a scatterplot and now would like to add its regression > line but it does not show. > Below, the code I have used. > > lm3 <- lm(data$S_pH_KCl2.5_BCx~data$B_OleicoPF_BCx_per) > plot(data$S_pH_KCl2.5_BCx, data$B_OleicoPF_BCx_per) > abline(lm3) > > I have been able to do the complete operation using the software > STATISTICA but it would be great to do it with R. > > If you require more details please get in touch. > > Thanks a lot! > Bea
By the look of things you have either the regression or the plot the wrong way round. I suspect it is the regression. So try: Either: ##lm3 <- lm(data$S_pH_KCl2.5_BCx~data$B_OleicoPF_BCx_per) lm3 <- lm(data$S_pH_KCl2.5_BCx_per~data$B_OleicoPF_BCx) plot(data$S_pH_KCl2.5_BCx, data$B_OleicoPF_BCx_per) abline(lm3) Or: lm3 <- lm(data$S_pH_KCl2.5_BCx~data$B_OleicoPF_BCx_per) ##plot(data$S_pH_KCl2.5_BCx, data$B_OleicoPF_BCx_per) plot(data$S_pH_KCl2.5_BCx_per, data$B_OleicoPF_BCx) abline(lm3) The point is that in lm(V~U) the variable "U" is taken as corresponding the the x-axis (independent variable), and the variable "V" to the y-axis (dependent variable). Similarly for plot(U,V). So, for lm3 <- lm(V~U), abline(lm3) will plot the fitted V-values (y-axis) against the U-values (x-axis). Your original code was equivalent to: lm3 <- lm(V~U) plot(V,U) abline(lm3) whereas it should be Either: lm3 <- lm(V~U) plot(U,V) abline(lm3) Or: lm3 <- lm(U~V) plot(V,U) abline(lm3) Hoping this helps, Ted. ------------------------------------------------- E-Mail: (Ted Harding) <ted.hard...@wlandres.net> Date: 18-Dec-2012 Time: 21:00:25 This message was sent by XFMail ______________________________________________ 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.
