liveBook · Manning

Shapley value

As explained in Machine Learning for Tabular Data: XGBoost, Deep Learning, and AI

A Shapley value is a cooperative-game-theory allocation that fairly assigns each participant a contribution across all possible coalitions.

A Shapley value fairly assigns each participant’s contribution across every possible coalition. For machine learning, SHAP values adapt this idea to assign each feature credit for a specific prediction. section 7.3

The practical interpretation follows three ideas:

  • Each feature’s contribution reflects its influence across different feature combinations. section 7.3
  • SHAP uses resampling to approximate the otherwise expensive calculation over all combinations. section 7.3
  • The resulting explanations support model debugging, feature engineering, bias analysis, and interpretability. section 7.3

Explaining an XGBoost prediction

An XGBoost model can produce SHAP values for each transformed feature, compare them with predictions, and present global importance through bar or violin plots. A JSON explanation can pair each feature’s original value with its SHAP contribution for narrative interpretation. section 7.3

Listing 7.19 SHAP values as an XGBoost output
from XGBoost import DMatrix
 
booster = model_pipeline['xgb'].get_booster()              #1
 
Xt = model_pipeline['processing'].transform(X)             #2
feature_names = (
    model_pipeline['processing']
    .get_feature_names_out()
)                                                          #3
Xd = DMatrix(Xt)                                           #4
 
shap_values = booster.predict(Xd, pred_contribs=True)      #5
preds = booster.predict(Xd)                                #6

Inspect the runnable XGBoost procedure for obtaining transformed features, feature names, predictions, and SHAP contributions. section 7.3

How Machine Learning for Tabular Data: XGBoost, Deep Learning, and AI covers it

How deep it goes
Defines coalition-based contribution, additive attribution, and resampling approximation without deriving the underlying mathematics.
Examples
Uses XGBoost predictions, SHAP importance and violin plots, and JSON records pairing transformed features with contributions.
What it assumes
Assumes a trained machine-learning model, transformed input data, predictions, and identifiable feature names.
What you can do after
Diagnose model behavior with SHAP and TreeSHAP outputs, visualizations, and per-instance feature-contribution explanations.
How it connects
Connects cooperative game theory with SHAP values, feature engineering, model debugging, bias analysis, and interpretability.

Also explained in

Compare how 2 books explain Shapley value →

Related concepts

This explainer was generated by Manning's knowledge graph from the text of Machine Learning for Tabular Data: XGBoost, Deep Learning, and AI. The section links point to the parts of the book it draws on.