Al,
I'd redo everything and report in the paper that your peculiar predictor
was contributing strongly to models that were built without excluding
this predictor. This is an important information: your models get
"confused" by the predictor (I'd consider this a lack of a certain kind
of robustness, but I'm not a statistician).
HTH
Claudia
Am 26.05.2011 14:42, schrieb El-Tahtawy, Ahmed:
I am trying to develop a prognostic model using logistic regression. I
built a full , approximate models with the use of penalization - design
package. Also, I tried Chi-square criteria, step-down techniques. Used
BS for model validation.
The main purpose is to develop a predictive model for future patient
population. One of the strong predictor pertains to the study design
and would not mean much for a clinician/investigator in real clinical
situation and have been asked to remove it.
Can I propose a model and nomogram without that strong -irrelevant
predictor?? If yes, do I need to redo model calibration, discrimination,
validation, etc...?? or just have 5 predictors instead of 6 in the
prognostic model??
Thanks for your help
Al
.
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Claudia Beleites
Spectroscopy/Imaging
Institute of Photonic Technology
Albert-Einstein-Str. 9
07745 Jena
Germany
email: claudia.belei...@ipht-jena.de
phone: +49 3641 206-133
fax: +49 2641 206-399
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