[R] SVM probability output variation
Anders Carlsson
anders.carlsson at immun.lth.se
Wed Oct 21 14:49:42 CEST 2009
Dear R:ers,
I'm using the svm from the e1071 package to train a model with the
option "probabilities = TRUE". I then use "predict" with "probabilities
= TRUE" and get the probabilities for the data point belonging to either
class. So far all is well.
My question is why I get different results each time I train the model,
although I use exactly the same data. The prediction seems to be
reproducible, but if I re-train the model, the probabilities vary some what.
Here, I have trained a model on exactly the same data five times. When
predicting using the different models, this is how the probabilities vary:
probabilities
Grp.0 Grp.1
0.7077155 0.2922845
0.7938782 0.2061218
0.8178833 0.1821167
0.7122203 0.2877797
How can the predictions using the same training and test data vary so much?
Thanks,
Anders
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