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docs: fix counterfactual-fairness.md's COMPAS numbers to the repo-canonical figures
The COMPAS "biased model" table cited Black 58.15% / White 28.37% / 29.78pp gap. Those numbers appear nowhere else in the repo. The canonical unfair.py COMPAS result, cited identically by README.md and 8+ other explainers, is Black 87.16% / White 0.40% / 86.77pp. Replaced the table with the canonical figures (and matched the "High-Risk Flag Rate" header wording used elsewhere). The surrounding causal-graph narrative (CustodyStatus proxy, prior arrests downstream of race, why dropping race alone didn't help) is unchanged and holds identically. Regenerated the page, package mirror, and llms-full.txt. Closes #551
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explainers/counterfactual-fairness.html

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@@ -217,7 +217,7 @@ <h3 id="the-formal-definition">The Formal Definition</h3>
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<h3 id="concrete-example-compas-recidivism">Concrete Example: COMPAS Recidivism</h3>
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<p>The <a href="../index.html#project-compas"><code>COMPAS/</code></a> audit in this repo is a direct illustration of counterfactual fairness violation - even without using the causal framework explicitly.</p>
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<p>COMPAS assigns recidivism risk scores based on features including prior arrest count, age at first arrest, and custody status. The biased model produces:</p>
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<div class="explainer-table-wrap"><table class="explainer-table"><thead><tr><th>Group</th><th>High-Risk Rate</th></tr></thead><tbody><tr><td>Black defendants</td><td>58.15%</td></tr><tr><td>White defendants</td><td>28.37%</td></tr><tr><td><strong>Fairness Gap</strong></td><td><strong>29.78pp</strong></td></tr></tbody></table></div>
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<div class="explainer-table-wrap"><table class="explainer-table"><thead><tr><th>Group</th><th>High-Risk Flag Rate</th></tr></thead><tbody><tr><td>Black defendants</td><td>87.16%</td></tr><tr><td>White defendants</td><td>0.40%</td></tr><tr><td><strong>Fairness Gap</strong></td><td><strong>86.77pp</strong></td></tr></tbody></table></div>
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<p>Now ask the counterfactual question. Take a Black defendant with 3 prior arrests. Ask: <em>if this person had been white, with the same underlying behaviour and the same 3 prior arrests, would their risk score be the same?</em></p>
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<p>The answer is no - and the reason is <code>CustodyStatus</code>, which the <a href="proxy-variables.html">proxy variables explainer</a> identifies as the key proxy. Black communities have been subject to historical over-policing: for the same underlying behaviour, Black individuals are arrested at higher rates than white individuals. Prior arrest count is therefore not causally independent of race - it is partly <em>caused</em> by race, via differential policing. A model trained on prior arrests is therefore using a variable that race, in part, caused.</p>
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<pre><code>Race ──→ Policing intensity ──→ Arrest rate ──→ Prior arrests ──→ Risk score</code></pre>

explainers/counterfactual-fairness.md

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@@ -62,11 +62,11 @@ The [`COMPAS/`](../COMPAS/) audit in this repo is a direct illustration of count
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COMPAS assigns recidivism risk scores based on features including prior arrest count, age at first arrest, and custody status. The biased model produces:
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| Group | High-Risk Rate |
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| Group | High-Risk Flag Rate |
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|-------|---------------|
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| Black defendants | 58.15% |
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| White defendants | 28.37% |
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| **Fairness Gap** | **29.78pp** |
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| Black defendants | 87.16% |
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| White defendants | 0.40% |
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| **Fairness Gap** | **86.77pp** |
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Now ask the counterfactual question. Take a Black defendant with 3 prior arrests. Ask: *if this person had been white, with the same underlying behaviour and the same 3 prior arrests, would their risk score be the same?*
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faircode/_explainers/counterfactual-fairness.md

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@@ -62,11 +62,11 @@ The [`COMPAS/`](../COMPAS/) audit in this repo is a direct illustration of count
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COMPAS assigns recidivism risk scores based on features including prior arrest count, age at first arrest, and custody status. The biased model produces:
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| Group | High-Risk Rate |
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| Group | High-Risk Flag Rate |
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|-------|---------------|
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| Black defendants | 58.15% |
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| White defendants | 28.37% |
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| **Fairness Gap** | **29.78pp** |
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| Black defendants | 87.16% |
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| White defendants | 0.40% |
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| **Fairness Gap** | **86.77pp** |
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Now ask the counterfactual question. Take a Black defendant with 3 prior arrests. Ask: *if this person had been white, with the same underlying behaviour and the same 3 prior arrests, would their risk score be the same?*
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llms-full.txt

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@@ -3294,11 +3294,11 @@ The [`COMPAS/`](../COMPAS/) audit in this repo is a direct illustration of count
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COMPAS assigns recidivism risk scores based on features including prior arrest count, age at first arrest, and custody status. The biased model produces:
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| Group | High-Risk Rate |
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| Group | High-Risk Flag Rate |
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|-------|---------------|
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| Black defendants | 58.15% |
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| White defendants | 28.37% |
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| **Fairness Gap** | **29.78pp** |
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| Black defendants | 87.16% |
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| White defendants | 0.40% |
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| **Fairness Gap** | **86.77pp** |
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Now ask the counterfactual question. Take a Black defendant with 3 prior arrests. Ask: *if this person had been white, with the same underlying behaviour and the same 3 prior arrests, would their risk score be the same?*
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