I’ve read several forum posts and almost have the answer to this.

I am training a TMultiLayerPerceptron - I have a tree with many more background events than signal events. So I need to set a weight to account for this as stated eg here:

If I call TTree:SetWeight(), then it sets a weight for all the events in the TTree. How do I apply a weight to individual events, or even better, to events with a certain criterion?

many thanks


answering my own question, I believe Christophe already addressed this here:

This might be something to update the documentation with…

all the best
Peter Cogan