Laplace-AI-Research/cournot-cold-8b

Cournot-Cold 8B

A calibrated probability estimator for binary questions about future events. Given a question, its resolution criteria, its scheduled resolution date and an as_of date, it returns a probability in [0, 1]. It conditions on the question text alone — no retrieval, no news, no market price.

LoRA adapter + scalar regression head on Qwen/Qwen3-8B.

Weights: Laplace-AI-Research/cournot-cold-8b on the Hugging Face Hub — LoRA adapter, 349 MB. Smaller sibling: Cournot-Cold 4B — trained on the same 81,870 questions with the same targets, seed and footing, and statistically indistinguishable from this model on four independent axes: dev (n=3,000, Brier delta +0.0010 [−0.0020, +0.0040]), the published split (n=277), off-venue on Kalshi (n=778, −0.0064 [−0.0129, +0.0000]), and across seeds. Its transfer results are now measured on that model rather than inherited from this one. Take the 4B — half the base model, fits a 16 GB card, and on accuracy they are the same model. Evidence: Laplace-AI-Research/cournot-cold-8b on GitHub — the eval splits behind every claim, this model's raw forecasts (including the venue transfers where it failed), the metric code, and verify.py, which recomputes every number below without a model or a GPU.

The training corpus is not redistributed; DATASHEET.md documents its composition, collection and known defects in its place. See Training data provenance and licensing.

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The headline number

Brier 0.1893 on 277 questions that resolved after a freeze date committed in writing before it passed.

Reported the way the field's benchmark maintainers ask for it — a raw Brier with its corpus, base rate and horizon attached, plus the decomposition — rather than as a skill score against our own baseline. (ForecastBench built a difficulty-adjustment methodology specifically because naive Brier/BSS comparisons across different question sets have a rank correlation to true skill of only ~0.64.)

	published (headline)	dev (iteration only)
n	277	3,000
Brier	0.1893	0.1674
base rate	0.4946	0.3970
base-rate Brier (uncertainty)	0.2500	0.2394
Murphy calibration ↓	0.0048	0.0010
Murphy resolution ↑	0.0627	0.0718
ECE, equal-width / equal-mass (10 bins)	0.0558 / 0.0525	0.0233 / 0.0260
distinct output values	83	99
forecast sd	0.250	0.283
BSS vs base rate (diagnostic, not a comparability claim)	+24.3%	+30.1%

Calibration is somewhat worse on published than on dev (ECE 0.056 vs 0.023) and resolution is lower (0.063 vs 0.072). Both are what a smaller, harder, forward- accumulating split tends to look like; neither currently rests on a single bin. See Known weaknesses.

These numbers replaced an earlier set on 2026-08-27, and the reason is worth your attention. The published split was found to be feeding the model each question's actual resolution date in place of its scheduled close — information not available at as_of. The split was rebuilt and the model re-scored. Full disclosure below under The defect we found in our own evaluation.

For context, not as a comparison

ForecastBench's live baseline leaderboard (no tools, no retrieval) at time of writing: superforecaster median 0.103, o3 0.145, Qwen3-235B-A22B 0.167, Llama-3-8B-chat 0.178, zero-shot GPT-4 without retrieval 0.206. These are different questions, a different base rate, and a different horizon. They tell you the band we are in, not a ranking. We intend to submit to that leaderboard so a real difficulty-adjusted comparison exists.

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Contamination

Zero of the 3,000 dev questions and zero of the 277 published questions resolved before the base model was released. Outcome memorisation is therefore closed by construction, not by argument.

• Freeze: 2026-08-15, committed in a dated, public git history before it passed. Anyone with the repository and a clock can check that nothing in the published split resolved before we committed to the freeze.
• The split is gated on Qwen3-8B's public release date (2025-04-29), not on a stated pretraining cutoff. This is deliberate: Qwen3-8B publishes no data cutoff — not in the technical report, not on the model card. A release date is externally checkable; a cutoff is a vendor claim.
• 88% of published questions (243/277) also opened after that release date, and score BSS +20.9% on their own — so the result does not rest on questions that existed before the base model shipped.

What this does not establish, and what has since been tested. The published split is Manifold-only, so on its own it shows the skill is not memorised Manifold outcomes but cannot rule out a Manifold-specific artifact.

That second question has now been tested directly on a different venue — see Transfer — and the venue-specific reading is refuted: on Kalshi Politics the model discriminates better than it does at home. What remains is not a venue limit but a subject-matter one.

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Where it works, and where it does not

Forecasts are made at question open and compared against the Manifold crowd price read at a fraction φ through each question's life. This is deliberately unfair to us — the crowd has seen news we have not.

horizon	crossover φ*	our BSS at φ=0.10	crowd BSS at φ=0.10
under 7 days	never beats the crowd	+6.9%	+15.6%
7–30 days	0.31	+26.6%	+21.9%
30–120 days	0.46	+33.6%	+20.8%
120+ days	0.62	+44.3%	+19.4%

The supported claim: on questions with a horizon beyond 30 days, this model beats the Manifold crowd from question open through roughly the first half of the question's life; past 120 days, through about 62% of it, at more than twice the crowd's skill against the base rate. On questions resolving within a week it never beats the crowd at any point.

The mechanism: the crowd's skill is roughly horizon-invariant (+15.6% → +19.4% across the whole range) while ours rises steeply (+6.9% → +44.3%). We do not win because the crowd degrades on long-horizon questions — we win because we improve and it stays flat.

The crowd-parity claim above is Manifold-only — we have no price-series comparison on another venue, so "beats the market" is not a claim this model makes. The skill claim is broader and is set out under Transfer; the parity claim is not.

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Transfer

Skill crosses venues. It does not cross question types, and it does not reach subjects without a public track record.

Tested on 778 Kalshi judgment questions — a different venue, real money, long-horizon (median lifetime 62 days), 99% opened after the base model's release, and matched to the question shape this model is for.

	n	Brier	calibration	resolution	95% CI	BSS
Manifold dev (home venue)	3,000	0.1674	0.0010	0.0718	—	+30.1%
Kalshi — Politics	209	0.0789	—	0.1194	[0.0886, 0.1565]	+56.0%
Kalshi — Science & Technology	43	0.0902	—	0.0844	[0.0227, 0.1514]	−6.9%
Kalshi — Economics	63	0.2074	—	0.0686	[0.0355, 0.1248]	+1.6%
Kalshi — Elections	461	0.2278	—	0.0080	[0.0044, 0.0215]	−23.1%
Kalshi — all	778	0.1780	0.0345	0.0375	[0.0278, 0.0510]	+2.2%
Polymarket (mechanical questions)	3,000	0.2059	0.0239	0.0048	—	−9.9%

On Kalshi Politics the model discriminates better off-venue than at home — resolution 0.1194 against 0.0718, with an interval whose lower bound sits above the home figure.

Read the aggregate with care. The all-Kalshi row (+2.2%) is a composition artifact: 59% of that corpus is obscure local elections dragging down a stratum that beats the home venue. Neither number alone is honest; both are given.

Calibration does not transfer even where discrimination does. ECE is 0.156 on Kalshi against 0.023 on Manifold dev. A new venue needs its own calibration mapping, fit on that venue's own development split.

The contamination-free Kalshi subset, where this model does not beat a constant

The 778 above include questions that resolved before the training freeze. 117 of them resolved after it (resolved_at > 2026-08-15T00:00:00Z), and that subset is contamination-free by the same rule as the published split. It is also the least flattering number in this card, so it is stated rather than omitted.

	n	Brier	resolution
Cournot-Cold 8B	117	0.2064	0.0356
a constant at the base rate (0.2308)	117	0.1775	0.0000

Paired bootstrap, 10,000 draws, clustered on question_id (each of the 117 is its own event_ticker, so question-level resampling is the cluster bootstrap):

model minus constant: +0.0289 [-0.0109, +0.0673] — not significant.

Read this as: on 117 contamination-free out-of-venue questions, this model is statistically indistinguishable from predicting the base rate on every one. The point estimate is worse than the constant; the interval spans zero, so the honest claim is indistinguishability rather than a loss.

The subset is small and lopsided — 88 of 117 are Elections, the stratum the table above identifies as this model's worst — so it should not be read as a verdict on the venue. It should be read as: the transfer result above rests partly on pre-freeze questions, and the clean slice of it does not show skill.

Known weaknesses

Named specifically, because a limitations section that hedges generically is not a limitations section.

1. It needs the question's subject to have a public reference class. This is the sharpest limit, and it is not a venue limit — see Transfer.

On 461 Kalshi Elections questions the model collapses to resolution 0.0080 [0.0044, 0.0215], BSS −23.1%. Those questions name obscure individuals in local races — "Will Peter Chatzky be the Democratic nominee for NY-17?", "Who will win the 2026 Ann Arbor Democratic mayoral primary?" There is no reference class for such a name in a text-only prior. That is a lookup, not a forecast, and this model cannot perform it.

The same limit explains most of the Polymarket result below.

2. It cannot do mechanical threshold or counting questions. Questions of the form "Will Trump say 'X' this week?" or "Will TSA passengers on Feb 15 be between 1,500,000 and 1,700,000?" need a time series and precise arithmetic, not a judgment prior. Frontier models score 13.5–16.0% on date-duration arithmetic against 58.6–76.3% on date addition (Test of Time, Table 8). Independently corroborated off-venue: 48% of a real-money venue's own judgment-category markets are numeric-threshold questions, and they are the half we cannot do.

3. It is weakest on sports. On a keyword-identified sports subset (236 questions, 8% of dev): Brier 0.2379, resolution 0.0320, BSS +4.8% — against +32.0% on everything else. Manifold publishes no category or tag metadata, so this subset was identified by text keywords and under-recalls; treat 8% as a lower bound and the subset as approximate. We report it because the opposite worry (that the headline was propped up by sports) is a reasonable one and the data refutes it — excluding sports raises the aggregate.

4. Calibration is worse on published than on dev, ECE 0.056 vs 0.023, and resolution is lower, 0.063 vs 0.072. No single bin is responsible: the largest equal-width reliability gap is −0.184 in the 0.2–0.3 band at n=13, and the mid-range bands that carry most of the mass are close — 0.5–0.6 is n=47 at −0.030, 0.4–0.5 is n=63 at −0.097.

An earlier version of this card attributed the published-split calibration gap to one 13-question bin at 0.52–0.59. That bin does not survive the corrected split (see below); the gap is now smaller and diffuse rather than concentrated. We are recording the change rather than quietly restating the conclusion.

The honest reading at n=277 is that published is a smaller and somewhat harder sample than dev, not that a specific defect has been located. It will be re-checked as the split accumulates — the forward accrual is the only thing that settles it.

5. It is trained at a single as_of. Every training example uses as_of = open_date, so the model is off-distribution at any later as_of and degrades as as_of moves toward resolution. A varied-as_of training arm was run and failed: it flattened the horizon curve by hedging, losing resolution at every φ. The defect stands, unfixed.

6. Single model, no ensemble. Calibration under distribution shift is the known fragile regime for single models (Ovadia et al.); ensembling was the only method they found robust. We do not ensemble.

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Intended use

In scope. Binary questions about future events that are (a) long-horizon, beyond ~30 days, and (b) about subjects with a public track record — an institution, an office, a well-known organisation or person. A cheap prior to be updated by other evidence; cold-start estimates where no market exists; research on calibration and forecasting. Validated on two independent venues (Manifold, Kalshi) under those two conditions.

Out of scope.

• Questions resolving within a week — it never beats the crowd there.
• Mechanical threshold, counting or arithmetic questions.
• Questions about subjects with no public reference class — a local primary candidate, a private individual, an obscure entity. This is the sharpest limit and the model gives worse than base-rate answers in this regime.
• Any new venue without a fresh calibration mapping. Discrimination transfers; calibration does not.
• Any setting where a miscalibrated probability causes harm — this model has no evidence channel and cannot know anything that happened after its base model was trained.

Never use it as the sole input to a consequential decision. It is a prior.

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Evaluation data

• published (headline, n=277) — Manifold questions resolving after 2026-08-15. Never trained on, contamination-free by construction. Accumulates forward; the only source of an external number. Built by scripts/published_eval_set.py, which refuses any question whose scheduled close time is unknown rather than substituting a default — see below for why that refusal exists.
• dev (n=3,000) — resolving 2025-08-15 to 2026-08-15. Gates iteration. Never published as a headline claim.
• Parity (n=1,741) — the subset with a usable price series, for crowd comparison at five values of φ. Each question appears once per φ; rows are not independent and must be compared within φ, paired on question id.

All intervals are paired, question-clustered bootstraps (10,000 resamples). Seed-to-seed noise on this setup is ±0.003 Brier, so smaller differences are not findings.

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The defect we found in our own evaluation

On 2026-08-27, before this model was released publicly, we found that the published evaluation split had been feeding the model information it could not have had.

What it was. Every forecast prompt carries a resolution date. The date a forecaster actually has at as_of is the question's scheduled close. Our published split was supplying the date the question actually resolved — on 132 of 132 rows. The corresponding figure on dev, which is built from a different source, was 37.7%.

How it happened. The script that collects post-freeze questions from the Manifold API recorded the title, resolution and creation time but dropped closeTime, a field present in the same API response. With no close time available, whatever built the eval set filled the gap with the resolution time.

Why it went unnoticed. published_eval.json had no builder script. It entered the repository as a committed JSON file with no code behind it, so it could not be regenerated, diffed or reviewed. The defect lived in the one artifact in the pipeline nobody could reproduce. That is the part we consider most instructive.

What we fixed. The collector now captures closeTime; a backfill recovered it for questions already gathered; and the split is now built by scripts/published_eval_set.py, which refuses a question with no close time rather than defaulting one, because defaulting is how the defect entered. The builder reproduces the previously shipped rows field-for-field and is mutation-tested.

What changed, and what we cannot claim. The corrected split is larger (277 vs 132, partly from forward accrual) and its fields now match dev's semantics (41.9% vs 37.7% coincidental matches), so the two are commensurable for the first time. Headline Brier moved 0.1800 → 0.1893, calibration 0.0241 → 0.0048, ECE 0.104 → 0.056.

We cannot attribute those changes to the fix. On the 132 questions common to both, holding weights and adapter constant and changing only the prompt field, the paired question-clustered interval is +0.0070 Brier [−0.0155, +0.0330] and −0.0118 resolution [−0.0376, +0.0143] — both spanning zero, and underpowered: the Brier half-width is 3.5× the effect, and detecting it would need n≈1,584. The difference between the old and new headline is dominated by the split containing different questions, not by the correction.

So the honest statement is not "the old number was inflated." It is: the old number was produced under a defective input, and the magnitude of that defect is below what this sample can measure. The fix is justified by the leak itself, not by its measured effect.

Derivation sits in an internal decisions log which is not public. Everything needed to check the claim is in this repository: the corrected split, the regenerated forecasts, and verify.py.

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Training

• Base: Qwen/Qwen3-8B (Apache 2.0), LoRA r=32 α=64 dropout=0.05, all-linear, plus a trainable scalar head (modules_to_save=["score"]).
• Objective: Brier/MSE loss on a scalar output against the terminal 0/1 outcome. Under a proper scoring rule a 0/1 label is an unbiased Bernoulli observation; on our corpus it beat a lower-variance market-price target on resolution, because the price target is biased.
• Corpus: 81,870 resolved Manifold questions, all resolving before 2025-08-14.
• Footing: chat template on both train and score. This is load-bearing — a mismatch here silently invalidated an earlier headline result — and was re-established empirically by reproducing stored forecasts (mean abs diff 0.0018 with template, 0.2015 without).
• Padding: right. The head pools the last non-pad token — the opposite convention from generation.
• Calibration: none applied. The head's raw sigmoid(logit) is the shipped probability -- scalar_score.py applies no post-hoc mapping, and no fitted calibrator is distributed. An earlier version of this line claimed beta calibration fit on dev; that step was never part of the pipeline. The calibration figures above are therefore what the head produces untuned, which is a stronger result than the original claim, not a weaker one.
• Seed: replicated. A second full-corpus run at seed 20260828 differs by +0.0012 Brier [−0.0016, +0.0041] — not significant, half-width at the ±0.003 noise floor. The shipped number is not one seed's luck.

Reproduction note: transformers >= 4.51.0 is required for Qwen3ForSequenceClassification; config.pad_token_id must be set explicitly.

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Training data provenance and licensing

The corpus is derived from the Manifold Markets public API.

Manifold's terms restrict bulk API data to personal and non-commercial use, and state that it may not be used to train machine learning models for commercial purposes without a data licence (data@manifold.markets). This adapter is released under CC BY-NC 4.0 on that basis — research and non-commercial use. Anyone intending commercial use must obtain that licence from Manifold independently; it is not ours to grant.

The raw corpus is not redistributed. A datasheet describing its composition, collection and known defects is published in its place.

The base model's own licence (Apache 2.0) is unaffected and permits commercial use of the base weights.

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Reproducing

Every headline number in this card is recomputed from the shipped forecasts by verify.py — no model, no GPU, no network:

uv run python verify.py

To regenerate those forecasts from the weights instead:

uv run python scripts/scalar_score.py \
  --adapter Laplace-AI-Research/cournot-cold-8b \
  --set eval/published_eval.json \
  --out published.jsonl \
  --chat-template

Every eval run writes a manifest carrying model hash, data snapshot hash, eval split id and git SHA. Numbers without a manifest are not comparable.

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Citation and provenance of claims

Every number in this card is recomputed from the shipped forecasts by verify.py — no model, no GPU, no network. That is the check that matters, and it is the one you can run.

Behind it sits an internal decisions log, not public, which also records the results that failed: a varied-as_of arm that hedged, a mixed-venue arm that traded Manifold resolution for Polymarket robustness, two claims that died under a paired bootstrap, a leak found in this project's own published split, and a citation retracted after we could not find it in the paper we had attributed it to. Nothing in this card depends on that log — every claim here is either reproducible from the files in this repository or stated as unverified.