Dear R-list

 

Suppose I have a data set stored in hmet, for which I did get confidence
limit on a linear regression as shown below.

My question is how I can subset only data points which are within the
confidence limit.

 

Thank you. 

Keun-Hyung 

 

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Al=rnorm(100, 3)

Cd=rnorm(100, 0.2)

hmet=data.frame(Al=Al, Cd=Cd)

plot(Al, Cd, xlab="Al", ylab= "Cd", , pch=16)

cd.lm=lm(Cd~ Al, na.action=na.omit, data= hmet)

abline(cd.lm$coeff, lty=1)

xy= data.frame (Al =pretty(hmet$Al, 20))

yhat=predict(cd.lm, newdata=xy, interval="confidence")

ci=data.frame(lower=yhat[,"lwr"], upper=yhat[,"upr"])

lines(xy$Al, ci$lower, lty= 2, lwd=2, col="grey")

lines(xy$Al, ci$upper, lty=2, lwd=2, col="grey")


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