Re: Centering (was Re: Missing covariates)

From: Lewis B. Sheiner Date: July 03, 2001 technical Source: cognigencorp.com
From: LSheiner <lewis@c255.ucsf.edu> Subject: Re: Centering (was Re: Missing covariates) Date: Tue, 03 Jul 2001 13:27:09 -0700 Tsk, tsk, Nick. Consider the following experiment: Data = (x=1, y=1) 1. Fit to Y = a + bX SE(a) = inf. 2. Fit to Y = a + b(X-1) SE(a) = 0* * (If you insist on using Nn-1 to compute sigma, then imagine the data are N>1 replications of the (1,1) point) The point is that centering IS a reparameterization (in the ideal case, to parameters that are both more meaningful and less correlated than before). LBS. -- _/ _/ _/_/ _/_/_/ _/_/_/ Lewis B Sheiner, MD (lewis@c255.ucsf.edu) _/ _/ _/ _/_ _/_/ Professor: Lab. Med., Bioph. Sci., Med. _/ _/ _/ _/ _/ Box 0626, UCSF, SF, CA, 94143-0626 _/_/ _/_/ _/_/_/ _/ 415-476-1965 (v), 415-476-2796 (fax)

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Jul 02, 2001 Nick Holford Centering (was Re: Missing covariates)
Jul 02, 2001 William Bachman RE: Centering (was Re: Missing covariates)
Jul 02, 2001 Kenneth G. Kowalski RE: Centering (was Re: Missing covariates)
Jul 02, 2001 Lewis B. Sheiner Centering (was Re: Missing covariates)
Jul 03, 2001 Jogarao Gobburu Re: Centering (was Re: Missing covariates)
Jul 03, 2001 Alan Xiao Re: Centering (was Re: Missing covariates)
Jul 03, 2001 Nick Holford Re: Centering (was Re: Missing covariates)
Jul 03, 2001 Alan Xiao Re: Centering (was Re: Missing covariates)
Jul 03, 2001 Lewis B. Sheiner Re: Centering (was Re: Missing covariates)
Jul 03, 2001 Alan Xiao Re: Centering (was Re: Missing covariates)
Jul 03, 2001 Diane Mould Re: Centering (was Re: Missing covariates)
Jul 04, 2001 Nick Holford Re: Centering (was Re: Missing covariates)
Jul 04, 2001 Alan Xiao Re: Centering (was Re: Missing covariates)
Jul 04, 2001 Diane Mould Re: Centering (was Re: Missing covariates)
Jul 05, 2001 Nick Holford Re: Centering (was Re: Missing covariates)
Jul 05, 2001 Stephen Duffull RE: Centering (was Re: Missing covariates)
Jul 05, 2001 Nick Holford Re: Centering (was Re: Missing covariates)
Jul 05, 2001 Leon Aarons 70kg neonates
Jul 05, 2001 Nick Holford Re: 70kg neonates
Jul 05, 2001 Peter Bonate Centering
Jul 05, 2001 Alan Xiao Re: Centering (was Re: Missing covariates)
Jul 05, 2001 Leonid Gibiansky RE: Centering (was Re: Missing covariates)
Jul 05, 2001 Kenneth G. Kowalski RE: Centering (was Re: Missing covariates)
Jul 05, 2001 William Bachman RE: Centering (was Re: Missing covariates)
Jul 05, 2001 Diane Mould Re: Centering (was Re: Missing covariates)
Jul 05, 2001 Alan Xiao Re: Centering (was Re: Missing covariates)
Jul 05, 2001 Alan Xiao Question 2 about prediction and covariates
Jul 06, 2001 Matt Hutmacher RE: Centering (was Re: Missing covariates)
Jul 09, 2001 Vladimir Piotrovskij RE: Centering (Impact on SE)
Jul 09, 2001 Alan Xiao Re: Centering (was Re: Missing covariates)
Jul 09, 2001 Kenneth G. Kowalski RE: Centering (Impact on SE)
Jul 09, 2001 Vladimir Piotrovskij RE: Centering (Impact on SE)
Jul 09, 2001 Smith Brian P RE: Centering (Impact on SE)
Jul 09, 2001 Matt Hutmacher RE: Centering (was Re: Missing covariates)
Jul 12, 2001 Juan Jose Perez Ruixo RE: Centering (was Re: Missing covariates)
Jul 12, 2001 Juan Jose Perez Ruixo RE: Centering (was Re: Missing covariates)
Jul 12, 2001 Matt Hutmacher RE: Centering (was Re: Missing covariates)
Jul 12, 2001 Alan Xiao Re: Centering (was Re: Missing covariates)
Jul 30, 2001 Juan Jose Perez Ruixo Re: Centering (was Re: Missing covariates)
Jul 30, 2001 Alan Xiao Re: Centering (was Re: Missing covariates)
Jul 30, 2001 Leonid Gibiansky RE: Centering (was Re: Missing covariates)
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