In a binary classification task, I have a small training set (n=900, 9 features). The two groups are not symmetric (1 = 560, 0 = 340). I also have a test set (n=400) where I don't know the class variable.
Let's say I want to check if a SVM works fine. To estimate the best hypothesis I'll do cross-validation. How do I choose k?
If a choose k=10, I have a training set of 810 cases and a cv set of 90 cases. Bias is low but variance is high.
Does anybody know a rule of thumb in this kind of situation?