Hi,

I'm using R to analyse a data set. I have found confidence intervals and prediction intervals for my data. However i'm having trouble adding the confience intervals and prediction intervals to my scatter graph.

x=c(-0.5,-0.4,-0.3,-0.2,-0.1,0,0.1,0.2,0.3,0.4,0.5)
y=c(8.1,7.8,8.5,9.8,9.5,8.9,8.6,10.2,9.3,9.2,10.5)
plot(x,y,pch=16,xlab="Temp",ylab="Sugar",main="Sug ar remaining after fermentation")
x0=data.frame(x=21.75)
ci=predict(pull.lm1,newdata=x0,interval="conf")
cbind(x0,ci)
pi=predict(pull.lm1,newdata=x0,interval="pred")
cbind(x0,pi)
lines(x0$x, ci[,2],lty=2);lines(x0$x,ci[,3],lty=2)
lines(x0$x, pi[,2],lty=3);lines(x0$x,pi[,3],lty=3)

The last two lines show my attempt at adding the confidence and prediction intervals. These commands arn't working, my graph stays the same. I'd appreciate any help. Thanks.