[R] residuals from lm

chuck.01 CharlieTheBrown77 at gmail.com
Mon Jul 2 17:58:38 CEST 2012

I was playing around with something else and I noticed this matrix code for
residuals in a linear model doesn't say what lm() says.  Please tell me if I
am completely misguided here. 

Y <- as.matrix(mtcars[,1])
X <- as.matrix(mtcars[,c(2:11)])

# shouldnt this: 
H <- X %*% solve(t(X) %*% X) %*% t(X)
(diag(dim(H)[1]) - H) %*% Y

# be equal to this:

# ???      
# thanks

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