Dear All, When I plot the values and linear regression line for one data set, it is fine. But for another one I see zigzags, when I plot the confidence interval
>cd Depth CHAOsep12RNA 9,94 804 25,06 1476,833333 40,04 1540,561404 50,11 1575,166667 52,46 349,222222 54,92 1941,5 57,29 1053,507042 60,11 1535,1 70,04 2244,963303 79,97 1954,507042 100,31 2679,140625 > plot(cd$CHAOsep12RNA,cd$Depth, ylim = rev(range(0:100)), xlab="CHAO", > ylab="Depth", pch=15, las=2, main="Sep12-RNA", cex.main=1) > lmR <- lm(cd$Depth~cd$CHAOsep12RNA) > abline(lmR) pconfR <- predict(lmR,interval="confidence") matlines(cd$CHAOsep12RNA,pconfR[,c("lwr","upr")], col=1, lty=2) I also tried > newx <- seq(min(cd$CHAOsep12RNA), max(cd$CHAOsep12RNA), length.out=11) > a <- predict(lmR, newdata=data.frame(CHAO=newx), interval=c("confidence")) > plot(cd$CHAOsep12RNA,cd$Depth, ylim = rev(range(0:100)), xlab="CHAO", > ylab="Depth", pch=15, las=2, main="Sep12-RNA", cex.main=1) > abline(lmR) > lines(cd$CHAOsep12RNA, a[,2], lty=2) But I see both cases kind of zigzags. What can it be the reason? thank you!
zigzaging.pdf
Description: Adobe PDF document
______________________________________________ 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.