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Equation 2 · Part 1 · Ten Ways an Agent Evaluation Can Mislead You Even When It's Working Correctly

Symbol U

UU
UU

What this part means

the highest m selects simultaneously for high.

Its job in the formula

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

Where the article explains it

The simplest to state is regressional: if a proxy metric M relates to the true target U by M = U + ε\varepsilon for some error term ε\varepsilon uncorrelated with U , then selecting the run with the highest M selects simultaneously for high U and for large favorable ε\varepsilon — the optimizer is drawn toward the tail of the error term as reliably as toward genuine capability, and the more intensely M is optimized, the larger a share of the observed gain is ε\varepsilon rather than U .

The passage around this formula

…a formal taxonomy, distinguishing at least four distinct failure mechanisms grouped under Goodhart’s name rather than one [ 1 ] . The simplest to state is regressional: if a proxy metric M relates to the true target U by

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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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Sources cited in the surrounding passage

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