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Equation 24 · Part 1 · Why Average Success Rate Hides the Failures That Matter Most

Symbol k

kk
kk

What this part means

k is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Its job in the formula

k is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

The passage around this formula

A bound is not an estimate, though, and an operator usually needs more than an upper limit — they need to know roughly what the rate actually is, which requires observing the event itself, repeatedly, rather than merely failing to observe it. For a Poisson-distributed count of k observed tail events, the relative standard error of the resulting rate estimate scales as 1/k\sqrt{k} , so getting a usably precise estimate — a relative error in the neighbourhood of 20 to 25 percent, comparable to observing on the order of twenty events — requires

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A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

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