Dear fellow R-ussers,
Thanks for your help on th AIC.
I have yet an other question about logistic models. to buuild the model i 
used sevral packages, (MASS, nlme, binom), just to make sure i had all the 
tools at my disposal. now i would like to validat the model. ussing a 
cross validation tool.
In a normal logistical case you get an error table giving the number of 
cases classified under  0/1  by the model, and a comparison with the real 
classification of the test sample.

table 1
glm         0   1
FALSE  8 14
TRUE     0   8

Apperently this is not the case when you have categorical data. Then you 
get an output for every interval of your predictor variable , and this is 
compared to the frequency of this variable, so it is very hard to 
interpred.

table 2
glm         0 2 3 4 7
FALSE  1 0 0 1 1
TRUE     1 2 1 0 0
One of the problems is, not only that i can't interpret table 2, but also 
that it does not give reference to the number of test samples, wich is 
clear in table 1 ( 30 test samples).
Kind regards,
Tom.








 
Tom Willems
CODA-CERVA-VAR
Department of Virology
Epizootic Diseases Section
Groeselenberg 99
B-1180 Ukkel

Tel.: +32 2 3790522
Fax: +32 2 3790666
E-mail: towil@var.fgov.be

www.var.fgov.be 



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