Symbol m

The passage around this formula

The useful ordering is by expected loss. For a mode m with arrival rate $\lambda_m$ , mean time to detection $\tau_m$ , and cost per undetected instance $\ell_m$ , the loss accrued before anyone intervenes is approximately $L_m \approx \lambda_m \, \tau_m \, \ell_m$. and the marginal value of instrumentation is whatever it removes from $\tau_m$ . Written this way the ranking changes sharply from intuition, because $\tau_m$ varies over several orders of magnitude across the list while $\lambda_m$ and $\ell_m$ vary by much less. Detection latency, not frequency or severity, is what dominates.

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