2. Measuring in money#
A cost matrix on its own is not a number. A strategy decides how it becomes one, and the pair
becomes a Metric you can call like any scikit-learn scoring function.
If your problem is customer churn, acquisition or credit scoring, the last three pages ship the standard cost matrix for that domain — you may not need to write one at all.
The six strategies, what each one assumes about your scores, and which models can train on them.
What a Metric can do beyond returning a score: optimal thresholds and rates, missing
parameters, LaTeX.
The standard retention cost matrix, and the ready-made EMPC and MPC metrics built on it.
The standard acquisition cost matrix, and the EMPA and MPA metrics built on it.
The standard credit scoring cost matrix, and the EMPCS and MPCS metrics built on it.