Date:         Wed, 16 Aug 2006 09:20:30 -0500
Reply-To:     Gary Rosin <grosin@stcl.edu>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Gary Rosin <grosin@stcl.edu>
Subject:      Re: Loss function for log-likelihood nonlinear regression of
              proportion via Inverse Logit
In-Reply-To:  <002901c6c126$b1ffd7d0$a200a8c0@NOTEBOOK>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 06:25 AM 8/16/2006, Hector Maletta wrote:
>  The expression for non linear expression for the pass rate mentioned in
>your message is exactly the definition of the probability of passing the
>exam in logistic regression. Calling Z to the combination
>b1X1+b2X2+...+bnXn, that probability is exp(z) / 1 + exp(Z), and the b
>coefficients are the log odds ratios coefficients computed by logistic
>regression.


Yes.  In Nonlinear Regression that expression is what I use as the
'Model".  The default loss function in least-squares.  I'd like to use
log-likelihood instead, but don't know the expression for that loss
function.

Gary



     ---

Prof. Gary S. Rosin              Internet:  grosin@stcl.edu
South Texas College of Law
1303 San Jacinto                   Voice:  (713) 646-1854
Houston, TX  77002-7000           Fax:  (713) 646-1766