Comparing 2 similar regressions
Posted: Tue Apr 19, 2011 5:14 am
Hi all,
I am estimating a simple regression: Y = C(1) + C(2)*X (1)
Suppose I find that: X = X1 + X2
So that (1) can be rewritten as: Y = C(1) + C(3)*X1 + C(4)*X2 (2)
Now I am interested in investigating (but don't know how to, please help!):
1. Whether regressions (1) and (2) are the same, i.e. whether C(2) = C(3) + C(4)
My initial thoughts are (i) to set up a system, then use a Wald test, or (ii) to set up a new regression: Y = C(1) + C(2)*X + C(3)*X1 + C(4)*X2 and then use a Wald test. But I am really not sure if there are any problems with either approaches.
2. Whether decomposing X into X1 and X2 is better (or worse) in terms of explaining Y.
Thank you very much for any hints.
I am estimating a simple regression: Y = C(1) + C(2)*X (1)
Suppose I find that: X = X1 + X2
So that (1) can be rewritten as: Y = C(1) + C(3)*X1 + C(4)*X2 (2)
Now I am interested in investigating (but don't know how to, please help!):
1. Whether regressions (1) and (2) are the same, i.e. whether C(2) = C(3) + C(4)
My initial thoughts are (i) to set up a system, then use a Wald test, or (ii) to set up a new regression: Y = C(1) + C(2)*X + C(3)*X1 + C(4)*X2 and then use a Wald test. But I am really not sure if there are any problems with either approaches.
2. Whether decomposing X into X1 and X2 is better (or worse) in terms of explaining Y.
Thank you very much for any hints.