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Test 13 - But Why (Shapley)

Purpose

Produce Shapley explanations and global feature-importance visualizations for the model using the test cohort. Helps identify which features drive predictions and create per-feature explainability graphs.

Required Inputs

  • WORK_DIR: working directory containing repository and model artifacts
  • MODEL_PATH: path to the fitted model (expected ${WORK_DIR}/model/model.medmdl)
  • ${WORK_DIR}/rep/test.repository and ${WORK_DIR}/Samples/3.test_cohort.samples

How to Run

1
./run.specific.sh 13
Or run as part of the suite: 
1
./run.sh

What This Test Does

  • Requests SHAP values from Flow twice: grouped by signal category and ungrouped (full features). Outputs are written to ${WORK_DIR}/ButWhy/shapley_grouped.report and ${WORK_DIR}/ButWhy/shapley.report.
  • Uses feature_importance_printer.py to generate global HTML reports:
    • ${WORK_DIR}/ButWhy/Global.html (grouped)
    • ${WORK_DIR}/ButWhy/Global.ungrouped.html
  • Generates per-feature HTML files under ${WORK_DIR}/ButWhy/single_features/ by expanding the ungrouped SHAP report.
  • Patches HTML files to use a local Plotly JS (../js/plotly.js).

Output Location

  • ${WORK_DIR}/ButWhy/ - contains shapley.report, shapley_grouped.report, Global.html, Global.ungrouped.html, and single_features/ HTMLs.

How to Interpret Results

  • Global.html gives a ranked list of feature groups and their aggregate importance. Use it to identify which signal categories contribute most to the model.
  • single_features/ contains per-feature SHAP distribution plots useful for detailed investigation.

Troubleshooting

  • Missing model or repository: ensure MODEL_PATH and ${WORK_DIR}/rep/test.repository exist.
  • Flow failures: run the Flow --shap_val_request command manually to debug arguments (e.g.).
  • Plotly not loading: ensure ../js/plotly.js exists relative to the generated HTML; the test rewrites script tags to ../js/plotly.js.

Files to inspect

  • ${WORK_DIR}/ButWhy/shapley.report
  • ${WORK_DIR}/ButWhy/shapley_grouped.report
  • ${WORK_DIR}/ButWhy/Global*.html
  • ${WORK_DIR}/ButWhy/single_features/*.html