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TF-IDF + logistic regression

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The signed evidence record for tfidf_logreg. Everything below was read out of the passport file; the signature was checked when this page was built, by the same code the Verify button runs.

SIGNATURE VALIDexit 0signature valid, issued by NakedSignal under key ns-passport-2026-07, not expired
SubjectTF-IDF + logistic regression tfidf_logreg
Configuration1-2 grams, 200k features, sublinear tf
Code fingerprintb444c02112cc
Spec versionMedEval-1 v0.1
Issued2026-08-03T16:03:42Z by NakedSignal
Expires2026-09-20T00:00:00Zthe sealed held-out generation this evidence cycle is anchored to (gen2, set hash ad30d214daa285c5...) is published to expire 2026-09-20; per spec, a passport lapses when its generation retires or its spec version is superseded, whichever comes first
key ns-passport-2026-07 · Ed25519

The check runs against the public key published on the governance page, using your browser's own Ed25519 implementation. The exit code shown is the exit code verify_passport.py returns for the same document.

Measured by NakedSignal

Computed in this repo by the MedEval-1 harness on data the model had never seen. Every number below was copied out of a file the harness wrote — 8 of them, each listed with its SHA-256 at the foot of this panel — and is printed exactly as it was signed, not re-rounded for display.

TaskDomainn testaccuracycalibrationuncertaintysubgroupcorruptionacquisitionlimited datacostspec sensitivityIndex
jobpost_fraudlabour447059.44700593.84921399.699987093.518519n/a84.779189n/an/a69.637036
ledgarlegal1000069.52891418.58020793.431808097.620114n/a93.572337n/an/a60.466641
medabstractsmedicine288836.74065817.09195350.77828520.98662298.763387n/a78.825996n/an/a48.715873

Cross-site retention

not measured for this subject — it is only defined within a family of tasks that share a corpus and differ in acquisition, and this model was not run on one.

Private held-out track

this subject was not submitted to a sealed generation.

Known limitations

Subgroup metadataabsent on 2 of 3 corpora, so the subgroup score falls back to the worst diagnostic class. That absence is a disclosure, not a pass.
Training set cappedyes on at least one task — see the raw JSON for which
Observed in deploymentnothing — see the third panel

Audit chain

Bundles re-derived48 of 48
Ledger100 entries, head 6b7b371ff650a8ed, chain intact
Re-run it yourselfpython src/heldout/audit.py 1f66c7719ab3943c6fcc
8 source files, with hashes
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results/heldout/manifests/public.seal.json1a4fd930d2e781ac7163483990f15d6694e28e507d1b3ca009ff09395e47497c
results/records/jobpost_fraud__tfidf_logreg.json071b3197e278bad180c3f895cf19115b36261e2b21de345521516d2a7ea26b55
results/records/ledgar__tfidf_logreg.json48074b04804239b1794921d82d78f9ad02f33ebac0919e17b3d80a0256c00a56
results/records/medabstracts__tfidf_logreg.json5abf53a97a33bda6a880b1367822afcd41565ff890102de5b000c20e62a7d913
Declared by vendor

Five fields a vendor asserts about its own product — intended use, forbidden use, training cutoff, regulatory clearances, and who is personally attesting. NakedSignal never fills these in on a vendor's behalf.

No vendor declaration. This is an open reference baseline implemented by NakedSignal, not a commercial product: there is no vendor to assert an intended use or to sign an attestation, so the declared block is null rather than filled in on the vendor's behalf.

Observed in deployment

Production history and drift — how the model has actually behaved since it was deployed, on real traffic.

Not available: this requires continuous monitoring. Production history and drift are observed fields, and nothing is deployed, so there is nothing to observe. The object is present and null on purpose. The shape is the roadmap, not a claim.

Raw JSON — the whole signed document, 17,993 characters
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  "key_id": "ns-passport-2026-07",
  "name": "NakedSignal",
  "public_key_b64": "0PBCC6mjzcppR5QdPcK7vP/AamB6MP8l1T4ypMYbsMw="
 },
 "observed": null,
 "observed_note": "Not available: this requires continuous monitoring. Production history and drift are observed fields, and nothing is deployed, so there is nothing to observe. The object is present and null on purpose. The shape is the roadmap, not a claim.",
 "passport_version": "0.1",
 "signature": "38zCulbZ+JgacY94J0se1jjl7Kcpd7jn6fQ4pMdWphV7skM9D1Xwf8H1I2b1yE3lmxiU5W3IBGS6Gqn6cSnLCA==",
 "spec_version": "MedEval-1 v0.1",
 "subject": {
  "behaviour_version": "1.0.0",
  "code_fingerprint": "b444c02112cc",
  "code_fingerprints": [
   "b444c02112cc"
  ],
  "family": "classical",
  "model_id": "tfidf_logreg",
  "model_name": "TF-IDF + logistic regression",
  "params": "1-2 grams, 200k features, sublinear tf"
 }
}

Canonicalisation: RFC 8785 (JCS)-compatible: UTF-8, object keys sorted by code point, no insignificant whitespace, ECMAScript number formatting. every float is rounded once at emit to 6 decimal places (Python round(), banker's rounding); integers are left exact. Signed over the whole document with the `signature` member removed, canonicalised as above and encoded UTF-8. The public key for ns-passport-2026-07 is 0PBCC6mjzcppR5QdPcK7vP/AamB6MP8l1T4ypMYbsMw= — see Governance.