RE: OMEGA HAS A NONZERO BLOCK
From:"Kowalski, Ken"
Subject:RE: [NMusers] OMEGA HAS A NONZERO BLOCK
Date: Mon, 7 Oct 2002 13:05:17 -0400
All,
And my only quibble with Lewis' reply is what does it mean to "resort to
science"? Is there some scientific theory that says the correlation is
0.5?...I doubt it. If previous scientific exploration results in data that
is readily extrapolated to the current problem that supports a strong prior
for the correlation then I'm all for it (just show me the data...I sound
like I'm from Missouri but I'm not). I agree we "never know nothing"...but
what do we know and how well do we know it? Just to say that I know
theoretically that the correlation can't be 1 doesn't give me Carte Blanc to
fix it or specify a strong informative prior in the absence of any
additional information. I also agree that we are on tenuous grounds in
using models for prediction when we estimate elements of Omega on the
boundary. But we are also on tenous grounds for prediction if we fix it to
0.5 in the absence of any truly independent information to support this
prior. I have no problem with domain experts providing the 'extra
information' I just want to see the theory or prior data that supports this
information, otherwise, it just sounds like hyper-subjectivity to me.
Ken