Interpreting a reliability claim requires a named estimand, task and evaluation laws, artifact revision, inference protocol, evaluator version, sample rule, and failure policy. Missing coordinates are unknown rather than implicitly held fixed.

For a candidate evaluation item \(z\), a contamination record is

The fields identify source provenance, split membership, prior agent exposure, overlap evidence, and the admission decision; an absent field is an explicit unknown.

Given a contamination record \(c(z)\), write \(\operatorname {cont}(z)=1\) when its declared overlap or exposure rule rejects \(z\), and write \(\operatorname {cont}(z)=0\) when the rule clears it. The predicate belongs to the protocol, not to a model’s score.

For an evaluation law \(\mathsf Q\), an admitted slice is \(\mathcal Z_0=\{z:\operatorname {cont}(z)=0\}\). Its reported score is conditioned on the declared slice law; removing contaminated items does not preserve the original estimand unless the law is unchanged by construction.

A paired design fixes one evaluation law, one item order, and one sampling kernel for two artifacts, then records the paired difference from Definition [ftip-00FE]. Any item-level exclusion is applied before seeing the paired outcomes or is declared as an adaptive rule.

Under a fixed nonadaptive slice and the iid coupling of Definition [ftip-00FE], the paired estimator remains unbiased for the two marginal scores in Theorem [ftip-00FF].

If one paired run scores all ten items but a second run removes two items after inspecting outputs, the two means answer different questions. A report must expose the removal rule and the resulting slice law.

The measurement and paired-comparison guidance in [jarmak2026reliable], Part I, is a methodology source. It motivates contamination ledgers and matched comparisons; it supplies no universal contamination detector or statistical guarantee.