---
conjecture: r3-b1-04
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": "Apparent stability could be mechanical stock-flow dilution: the 499,003-row legacy stock is so large that even a compositionally extreme new batch may not move any cumulative category by 10 percentage points. Stability would then reflect denominator inertia rather than stable composition among new records.",
      "why_it_explains_the_same_evidence": "A small change between snapshots taken days apart would be almost invisible in the cumulative shares. Moreover, any extension below roughly 60,000 rows cannot shift even the most sensitive category by 10 points, regardless of its composition, so a future pass after modest growth would also be explained. No held-out result currently distinguishes this mechanism.",
      "named_confounds": [
        "stock-flow denominator inertia",
        "cumulative-versus-marginal composition",
        "extension-size effect"
      ],
      "discriminating_test": {
        "description": "For each future extension, identify genuinely new row IDs and compute category shares separately for the marginal batch and the cumulative catalogue. Compare marginal shares with the registered baseline using multinomial confidence intervals, while recording the dilution factor n/(499003+n).",
        "computable_on_held_data": true,
        "what_result_favors_rival": "A future cumulative mix remains within 10 points while one or more sufficiently large marginal batches differ from baseline by more than 10 points, with the cumulative change matching the predicted dilution by the legacy stock. The proposed stationary-growth mechanism instead predicts ordinary marginal additions should themselves approximately reproduce the baseline mix."
      }
    },
    {
      "mechanism": "The aggregate mix could be generated by recurring harvest weights across contributing institutions or metadata schemas. Schemas that omit a usable medium field would disproportionately produce unknown rows, while other schemas map predictably to the named classes; stable contributor weights would therefore reproduce the aggregate percentages without stable underlying material composition.",
      "why_it_explains_the_same_evidence": "The unusually large unknown share is compatible with schema-dependent missingness, and an essentially unchanged snapshot is expected if successive harvests preserve the same contributor or schema mixture. A future aggregate pass would likewise follow from recurring ingestion quotas even if the actual media represented within contributors changed. There is no held-out outcome yet to choose between these explanations.",
      "named_confounds": [
        "contributing-institution selection",
        "schema-dependent medium-field missingness",
        "automated metadata mapping",
        "harvest-batch composition"
      ],
      "discriminating_test": {
        "description": "Cross-tabulate medium_class by contributing institution, native schema or schema version, and landing batch. Fit a baseline model using stratum-specific category shares and predict later aggregate shares solely from later stratum row counts; compare its out-of-sample fit with a single source-wide stationary-share model. Also recompute each landing after standardizing all landings to common stratum weights.",
        "computable_on_held_data": true,
        "what_result_favors_rival": "Medium labels, especially unknown, are highly concentrated in particular contributor-schema strata; the stratum-weighted model materially outpredicts the source-wide model; and the registered aggregate stays stable while the standardized mix or within-stratum mix moves by more than 10 points. That would show that recurring administrative weights, rather than source-wide organic composition, generate the stability."
      }
    },
    {
      "mechanism": "Rows may be repeated holdings, copies, or child records expanded from a smaller set of parent bibliographic entities, with medium_class inherited from the parent. Stable category-specific record-multiplication rates could lock the row-level proportions even while the mix of newly catalogued unique works changes.",
      "why_it_explains_the_same_evidence": "The evidence reports rows rather than independent physical objects or unique works, so copied labels and recurring expansion factors can generate the observed counts and short-term stability. A future row-level pass would also occur if growth mainly adds children to existing record families in established ratios, even when genuinely new parent entities have a different medium mix. No held-out test has examined this distinction.",
      "named_confounds": [
        "unit-of-count effect",
        "hierarchical record expansion",
        "duplicate holdings or manifestations",
        "copy-forward classification"
      ],
      "discriminating_test": {
        "description": "Cluster rows into parent works or record families using explicit parent/work identifiers where available, supplemented by normalized title, creator, and date keys. Compute medium shares with one vote per family, estimate rows-per-family by category, and classify future additions as children of existing families or genuinely new families.",
        "computable_on_held_data": true,
        "what_result_favors_rival": "The cumulative row mix remains within 10 points, but the marginal mix among genuinely new families differs by more than 10 points; most added rows attach to old families; or category-specific rows-per-family factors explain the aggregate stability. The proposed organic-composition account would instead predict approximate stability among genuinely new entities, not only among multiplied rows."
      }
    }
  ],
  "no_viable_rival": false,
  "notes": "Because no held-out test has run, the unchanged measurement over a few days supplies little evidence beyond the single registered baseline; the eventual extension size and marginal composition will be essential for interpretation."
}
