covariance matrix

Sep 2009
41
0
This is a stupid question, but is this the formula to calculate the covariance matrix?

X'X? or is it the inverse of that?
 
Aug 2009
15
8
Sydney
the inverse of X'X is the variance-covariance matrix of the parameter estimates
 
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matheagle

MHF Hall of Honor
Feb 2009
2,763
1,146
I'm guessing what is being asked here is...

\(\displaystyle V(\hat\beta)=\sigma^2(X^tX)^{-1}\)

for the classical linear model.
 
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Sep 2009
41
0
yeahh well actually the question in my homework was actually what is the use of X'X? so i was just confirming it that could become the variance covariance matrix so i have something to say.

but thanks guys