Dear Subscribers,

I did fit an equation of the form 1 = f(x1,x2,x3) using a minimization

scheme. Now I want to compute the coefficient of determination. Normally

I would compute it as

r_square = 1- sserr/sstot with sserr = sum_i (y_i - f_i) and sstot =

sum_i (y_i - mean(y))

sserr is clear to me but how can I compute sstot when there is no such

thing than differing y_i. These are all one. Thus mean(y)=1. Therefore,

sstot is 0.

Thank you very much for your efforts,

Uwe

--

Uwe Wolfram

Dipl.-Ing. (Ph.D Student)

__________________________________________________

Institute of Orthopaedic Research and Biomechanics

Director and Chair: Prof. Dr. Anita Ignatius

Center of Musculoskeletal Research Ulm

University Hospital Ulm

Helmholtzstr. 14

89081 Ulm, Germany

Phone: +49 731 500-55301

Fax: +49 731 500-55302

http://www.biomechanics.de______________________________________________

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