AX-R10 — Supplier-supplied sample reads high against buyer-sourced

The index records how every sample was obtained, and the difference is measurable. Across all 88 lots where both a supplier-supplied sample and an independently purchased vial were assayed, the supplier-supplied result reads a mean 0.31 pp higher (95 % confidence interval 0.19 to 0.43 pp).

That average is small. This rule is about the tail: individual lots where the gap exceeds 0.8 pp, which is larger than inter-lab agreement, larger than within-lot vial variation, and larger than anything the method can explain.

Three mechanisms are consistent with a gap that size. The sample may be from a different fill than retail stock — several submitters have reported physically different vials, caps or fill volumes for samples. The sample may be from a hand-picked lot. Or the retail vial may have been degraded in a way the sample was not, in which case the finding is about distribution rather than about the supplier's honesty.

The index cannot separate these and does not claim to. What it does is publish the paired comparison, label the provenance of every record, and report every supplier's buyer-sourced subset separately from its total on the scorecard. Suppliers whose supplier-supplied fraction exceeds 25 % carry a note saying so.