[R] Drawing the regression line and the 95% confidence intervals

[Jim Lemon]

Hi Sacha,
The line you have requested is off the plot. The following will
produce what I think you are asking, but I cannot speak for whether it
means anything sensible.

plot(GDP.per.head, fitted(LinearModel.1),ylim=c(200,800))
devlm1<-lm(fitted(LinearModel.1)~GDP.per.head)
abline(devlm1)
conflm1<-confint(devlm1)
abline(coef=conflm1[,1],lty=2)
abline(coef=conflm1[,2],lty=2)

Jim


On Wed, May 6, 2015 at 8:01 AM, varin sacha <varinsacha at yahoo.fr> wrote:
> Hi, Dear R-helpers,
>
> Here below you will find a reproducible fictitious example working except the "abline" function.
>
> First thing : I try to draw the regression line (multiple linear regression). I try the "abline" function but it does not work. I don't get any error message but the straight line does not appear on the scatterplot.
>
> Second thing : I try to draw the 95% confidence intervals on the regression line. How could I do ?
>
> Using abline(0,1), I can of course add a line 45 degrees angle passing through the origin (intercept=0 and slope=1), but it is not what I am looking for.
>
> GDP.per.head=c(600,560,340,560,580,300,570,900,680,290,590,340)
> Quality.score=c(4.5,6.5,6,4.5,7,3,9,10,12.5,6.5,7,9)
> Competitivness.score=c(1000,1200,1400,700,680,1010,340,560,690,500,690,460)
> LinearModel.1=lm(GDP.per.head ~ Quality.score + Competitivness.score)
> plot(GDP.per.head, fitted(LinearModel.1))
> abline(GDP.per.head, fitted(LinearModel.1))
>
> Thanks for your help. Looking forward to reading you.
>
> Sacha
>
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