---
conjecture: r2-edh-b1-20
family: codex
model: "gpt-5.6-sol (codex-cli 0.144.0-alpha.4, ChatGPT-subscription auth)"
model_stamp_corrected: "2026-08-07 — archives were first written stamped gpt-5.5 by a runner bug (the stamper read config.toml's default instead of the -m flag actually passed). The calls themselves ran on gpt-5.6-sol throughout; only the label was wrong. Corrected in place, noted here rather than silently."
received: 2026-08-07
template: PROMPT_TEMPLATE_v1.md sha256 4344aabfacfe88362c56d89b6c89d594a7bf3a221e18a16b0e351482447e512f
rivals_parsed: 3
validation: VALID
---

{
  "rivals": [
    {
      "mechanism": "Coverage may primarily reflect the composition of each province's catalogued assemblage rather than cataloguing depth. Provinces dominated by monument-like stone inscriptions have an applicable, readily assigned type, whereas provinces containing many small finds, instrumenta, or otherwise non-monumental records accumulate structurally blank values.",
      "why_it_explains_the_same_evidence": "Regional research and inclusion practices can produce provinces dominated by either readily typed monuments or record classes for which monument type is inapplicable or rarely supplied. Because both alphabetical halves can contain provinces with these contrasting assemblages, this compositional mechanism predicts extreme low and high coverage in both training and holdout data.",
      "named_confounds": [
        "artefact-class composition",
        "structural non-applicability of monument type",
        "selection into the catalogue",
        "denominator composition"
      ],
      "discriminating_test": {
        "description": "Using fields or independently coded descriptions that do not depend on monument-type completion, classify rows into comparable artefact classes and directly standardize every province to the same class distribution; also recompute coverage within a common class such as identifiable monumental stone inscriptions. Compare the standardized province range with the raw range.",
        "computable_on_held_data": true,
        "what_result_favors_rival": "The rival is favored if province differences largely disappear after class standardization, or if the under-30% and over-90% extremes cease to occur within the common artefact class. Persistent extremes among closely comparable records would favor province-level cataloguing depth."
      }
    },
    {
      "mechanism": "The missingness may be a legacy-source or import-schema artifact: different provincial corpora were ingested in batches whose source databases either supplied a compatible monument-type field or supplied none that could be mapped. Equally well-resourced cataloguing could therefore yield nearly complete or nearly empty fields depending on data provenance.",
      "why_it_explains_the_same_evidence": "If provinces are dominated by different source corpora or import batches, province-level coverage will appear sharply heterogeneous even though the operative cause is field availability and vocabulary mapping. Such batches need not align with the alphabetical split, so source-rich and source-poor extremes can readily recur in both halves.",
      "named_confounds": [
        "legacy-source schema compatibility",
        "bulk-import batch effects",
        "vocabulary-mapping failure",
        "missing-by-design metadata"
      ],
      "discriminating_test": {
        "description": "Recover source-corpus, bibliographic provenance, import-batch, or record-creation-cohort identifiers and model monument-type presence jointly by province and provenance. Examine provinces represented in multiple batches and batches spanning multiple provinces, then compare province effects before and after conditioning on provenance.",
        "computable_on_held_data": true,
        "what_result_favors_rival": "The rival is favored if coverage is nearly constant within source or import batches, changes sharply between batches inside the same province, and province effects mostly vanish after provenance adjustment. Persistent within-batch province effects would favor the proposed province-level curatorial mechanism."
      }
    },
    {
      "mechanism": "Real differences in preservation and recovery context may determine whether an object's monument type is physically inferable. Provinces yielding intact objects permit type assignment, while provinces yielding reused, displaced, or highly fragmentary material generate blanks even under equally thorough cataloguing.",
      "why_it_explains_the_same_evidence": "Taphonomy, reuse, and excavation context vary geographically and can create very large differences in the proportion of classifiable objects. Provinces with favorable and unfavorable preservation can occur in both alphabetical halves, reproducing both observed extremes without invoking unequal curatorial resources.",
      "named_confounds": [
        "preservation and fragmentation bias",
        "archaeological recovery-context differences",
        "differential reuse or displacement",
        "physical observability of monument type"
      ],
      "discriminating_test": {
        "description": "Blindly code fragmentarity and type-identifiability from EDH object descriptions or photographs without consulting the recorded monument-type field. Recalculate province coverage among objects judged highly identifiable and standardize provinces to a common preservation distribution.",
        "computable_on_held_data": true,
        "what_result_favors_rival": "The rival is favored if blanks concentrate among independently judged unidentifiable objects and the provincial extremes collapse among well-preserved, highly identifiable objects. Large provincial differences among equally identifiable objects would instead support differential cataloguing depth."
      }
    }
  ],
  "no_viable_rival": false,
  "notes": "The alphabetical holdout demonstrates that extreme province-level heterogeneity recurs, but it does not distinguish province-level resourcing from province-correlated case mix, provenance, or physical identifiability."
}
