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>cdDepth 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! -------------- next part -------------- A non-text attachment was scrubbed... Name: zigzaging.pdf Type: application/pdf Size: 2111 bytes Desc: not available URL: <https://stat.ethz.ch/pipermail/r-help/attachments/20130517/50fd982f/attachment.pdf>
On 2013-05-17 06:03, Ozgul Inceoglu wrote:> 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! >Sort your dataframe by x-values (CHAOsep12RNA). Peter Ehlers
Hello,
Try the following.
lmR <- lm(cd$Depth ~ cd$CHAOsep12RNA)
pconfR <- predict(lmR,interval="confidence")
pcR <- pconfR[order(pconfR[, 1]), ] # Add this line
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)
matlines(sort(cd$CHAOsep12RNA), pcR[,c("lwr", "upr")],
col=1, lty=2) #
changed
Hope this helps,
Rui Barradas
Em 17-05-2013 14:03, Ozgul Inceoglu escreveu:> Dear All,
>
> When I plot the values and linear regression line for one data set, it is
fine. But for another one I see zigzags, when I plot the confidence interval
>
>> cd
> Depth CHAOsep12RNA
> 9,94 804
> 25,06 1476,833333
> 40,04 1540,561404
> 50,11 1575,166667
> 52,46 349,222222
> 54,92 1941,5
> 57,29 1053,507042
> 60,11 1535,1
> 70,04 2244,963303
> 79,97 1954,507042
> 100,31 2679,140625
>
>
>> plot(cd$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!
>
>
>
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