RE: Bootstrap resampling! -> Randomization test

From: "Stephen Duffull" <sduffull@pharmacy.uq.edu.au> Subject: RE: Bootstrap resampling! -> Randomization test Date: Fri, 30 Mar 2001 14:16:13 +1000 Hi all To pose some simple questions. If model misspecification affects the validity of the likelihood ratio test (which is not an altogether unexpected finding) and when analysing actual data (rather than simulated data) we always have model misspecification, then the LRT will almost never be valid in real life. Therefore it would seem appropriate to ignore deltaOBJ values in a statistical sense altogether (ie not use them for hypothesis testing). Perhaps we should ask ourselves: when do we need statistical verification of our model? For non-nested models, when the LRT is inappropriate anyway, have we always required statistical verification? Certainly most publications that discuss non-nested models do not supply statistical validation for their choice. Do we need statistical verification when the covariate effect is biologically plausible and biologically significant - or do we need it when biological plausibility or significance cannot be assessed (if so then was the covariate that important anyway)? I would certainly be interested in any thoughts that the group may have on this, particularly in light of the discussion about bootstrap and RT. Regards Steve ================= Stephen Duffull School of Pharmacy University of Queensland Brisbane, QLD 4072 Australia Ph +61 7 3365 8808 Fax +61 7 3365 1688 http://www.uq.edu.au/pharmacy/duffull.htm