> 2) Is it a good idea to apply the ClassBalancer filter and a CostSensitive Classifier on the same dataset? I cannot see any side effects, but I wish to be sure I did not miss anything.
I would not use them together. It’s best to simply adjust the cost matrix for CostSensitiveClassifier.
By default, CostSensitiveClassifier does is internal reweighting based on the cost matrix anyway. Also, if you switch to the minimum expected cost approach in CostSensitiveClassifier, it assumes accurate class probability estimates, but if you modify the weights with ClassBalancer, the class probability estimates will be biased.
> 3) I would like to apply a filter and a costSensitive classifier with the wrapper method.
> This means that in the Classify panel I select:
> then I specify costSensitive-->RandomForest (in the classifier box)
> then I select ClassBalancer (in the Filter box).
> I get the following error:
> What does it mean? How can I fix it?
> When I apply the ClassBalancer filter from the Preprocess tab and then a cost-Sensitive classifier from the Classify tab, everything goes smoothly.
Hmm, this works fine for me in WEKA 3.8.1/3.9.1. Anyway, you don’t really need the combination (see above).