Dear R, I am currently trying to caculate the coefficient of determination for different quantile regression models. For example fit<-rq(Hrubra~SessileInvertebrates,tau=0.8, data=Q1) fit1<-rq(Hrubra~SessileInvertebrates,tau=0.8, data=Q2) etc Could someone please advise me how do you calculate the the sum of the weighted absolute deviations in the models for the formula R = 1-(Sum(f)/Sum(r)) I have looked all through the help files but the only example I can find is in Stata. Thanks in advance Beth Strain _________________________________________________________________ Your Future Starts Here. Dream it? Then be it! Find it at www.seek.com.au %2F%3Ftracking%3Dsk%3Ahet%3Ask%3Anine%3A0%3Ahot%3Atext&_t=764565661&_r=OCT07_endtext_Future&_m=EXT [[alternative HTML version deleted]]