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The passage around this formula

The general operation, activation patching, is usually reported as a normalised score rather than a raw difference, isolating exactly how much of the gap between clean and corrupted behaviour a given component set closes: $\text{score}(\mathcal C) = \frac{m_{\text{patch}}(\mathcal C) - m_{\text{corrupt}}}{m_{\text{clean}} - m_{\text{corrupt}}}$. where $m_{\text{clean}}$ and $m_{\text{corrupt}}$ are a chosen behavioural metric measured on the clean and corrupted runs, and $m_{\text{patch}}(\mathcal C)$ is that same metric after the activations of component set $\mathcal C$ are copied from one run into the other. A score near one means patching $\mathcal C$ alone restores nearly all of the clean behaviour; a score near zero means it restores almost none.

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