KPM-1: pre-registered, hash-verified election predictions
Most political-prediction models can be quietly reframed in their post-mortem. KPM-1 cannot. The SHA-256 of every prediction is committed to GitHub before voting opens, so anyone can verify after results land that nothing was retroactively adjusted.
What hash-pre-registration prevents
Quiet retraction
Without a public hash, a model can quietly retract predictions in close races and claim "we always said X". With a hash, the predictions are the predictions.
Headline-metric drift
Without it, the post-mortem can move the headline metric to whichever one came closest. With it, the metric was declared in advance.
Retro-explained bias
Known biases are listed publicly before results, not after, so failures can't be retro-explained as known limitations.
Manual override laundering
Every council where we override the raw model output is logged in data/manual_overrides_applied.json with reason and pre/post values.
7 May 2026 UK local council elections
136 councils, 65,000 personas, predictions hash-committed on 1 May 2026 before voting opened. On the BBC's official Projected National Share, KPM-1 had the lowest mean absolute error of any model in the field: KPM-1 2.96pp · YouGov 3.20pp · Opinium 3.20pp · 10-poll consensus 3.50pp · Electoral Calculus 5.00pp.
Verify the hash yourself
Anyone can re-hash the predictions JSON after results land and confirm the file matches what was published before voting:
sha256sum predictions.json
# Compare against the value in predictions/pre_registration_hash.txt
UK constituency spot-checks
UK pipeline output verified against known constituency demographics. Census-weighted persona generation lands within published Census 2021 marginals across ethnicity, education, and deprivation.
| Constituency | White British | Asian | Black | Level 4+ | IMD score |
|---|---|---|---|---|---|
| Hackney North | 34% | 10% | 21% | 52% | 30.95 |
| Birmingham Ladywood | 43% | 31% | 11% | 30% | 47.64 |
| Bradford West | 57% | 32% | 2% | 27% | 42.47 |
| Brigg and Immingham | 91% | 2% | 1% | 23% | 17.48 |
| Croydon West | 37% | 18% | 23% | — | 29.74 |
| Rhondda and Ogmore | 95% | 1% | 0% | — | 36.23 |
The methodology and the live data
KPM-1's nine-layer methodology is documented at the level of detail required for academic critique. The live results browser lets you drill into every council, ward by ward, with confidence tiers and win probabilities.