Using matrix notation, it can be shown varcov () = 2 (X'X) 1 What happens to this varcov matrix: a. When there is perfect

Using matrix notation, it can be shown

var–cov (β̂) = σ²(X'X)⁻¹

What happens to this var–cov matrix:

a. When there is perfect multicollinearity?

b. When collinearity is high but not perfect?