Output of evaluation metric for XGBoost - is it cumulative? On the 10th boosting round for XGBoost, I get an MAP of 0.32 on the test data. Does that reflect the performance of just that 10th tree? Or the performance of all 10 trees combined that have been created so far?
That reflects the performance of the boosting of the 10 trees together.
I do reccomend you this tutorial https://www.youtube.com/watch?v=sRktKszFmSk&amp;t=4s
Gradient boosting is well explained there.
Using as a predictor only the 10th tree will give you weird results, since it is fitted on the residual errors of the previous 9