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Hello everyone,
I'm using WinNonlin to perform compartmental pharmacokinetic modelling.
One of the diagnostics given as part of the pharmacokinetic output data
is "S with n degrees of freedom". Could somebody tell me what S is
referring to and, more importantly, the significance of the value?
Thanks in advance.
Wendy Ingram
Research Student
Pharmacy Department
Derriford Hospital
Derriford Road
PLYMOUTH
PL6 8DH
UK
Tel: (44) 1752-763414
Fax: (44) 1752-763418
email: wendy.ingram.-at-.phnt.swest.nhs.uk
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Wendy - WinNonlin provides "S" as the estimate of Sigma, the error term for
your optimization. It is used as a metric for quality of fit and in the
calculation of parameter standard errors and confidence limits. S is
calculated as the square root of (weighted sum of squares/degrees of
freedom).
You can find computational formulas for output quantities in the WinNonlin
help system and in printed documentation. WinNonlin users or other
interested parties can direct questions about WinNonlin or other Pharsight
Modeling, Analysis, and Design (MAD) products to MAD.Support.aaa.Pharsight.com
or consult our web site at www.Pharsight.com.
Regards, Jeff
Jeff Wald, Ph.D. | Manager, Scientific Support Services
Pharsight Corporation | MAD: Modeling Analysis and Design Division
5520 Dillard Drive, Suite 210, Cary, NC 27511, USA | www.Pharsight.Com
Direct: Jeff.Wald.-at-.Pharsight.com | Technical inquiries:
MAD.Support.-a-.Pharsight.com
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