Using Transaction Amount to Guide Learning in an Fraud Detection Machine Learning Model
Since you are using boosting models you can add something named monotonic constraints:
It is often the case in a modeling problem or project that the functional form of an acceptable model is constrained in some way. This may happen due to business considerations, or because of the type of scientific question being investigated. In some cases, where there is a very strong prior belief that the true relationship has some quality, constraints can be used to improve the predictive performance of the model.
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