Hi all

I'm dealing with a supervised binary classification issue. I'd like to use
the GBM package to classify individuals as uninfected/infected. I have 15
times more uninfected than infected individuals.

I was wondering if GBM models suffer in the case of imbalanced class sizes?
I didn't find any references answering this question.

I tried to adjust the weights by assigning a weight of 1 to the uninfected
individuals and a weight of 15 to the infected, but I obtained poor results.

Thank you for your help

Yohann

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