Meridian Changelog
Model version history and quarterly test results.
v6.11
8 March 2026 Current ProductionTested against 295,026 H2-2025 Land Registry transactions
H2-2025 out-of-sample bulk test
| PE5 | PE10 | PE15 | PE20 | MdAPE | Bias | FSD |
|---|---|---|---|---|---|---|
| 39.6% | 65.4% | 79.8% | 87.6% | 6.7% | +1.92% | 25.2% |
Accuracy by FSD (Fitch) band
| Band | n | PE10 | MdAPE | Bias |
|---|---|---|---|---|
| Band A | 0 | — | — | — |
| Band B | 143,546 | 70.4% | 6.0% | -0.7% |
| Band C | 123,787 | 63.9% | 7.0% | +1.7% |
| Band D | 27,693 | 46.4% | 11.2% | +16.5% |
What changed from v6.10
Added spatial comparable pricing from nearby similar properties, weighted by similarity and adjusted for house price growth. +0.55pp PE10.
Also in v6.11: per-property FSD mapped to Fitch classification bands (A–D). FSD lookup table segmented by confidence decile, property type, and price band. Per-property SHAP contributions replacing global feature importance. FSD lookup recalibration against 100,938 backtest properties.
June 2026: proprietary confidence-tier overlay retired; the FSD/Fitch bands are now the sole confidence expression.
v6.7
7 March 2026What changed
Replaced national ONS House Price Index with a hyperlocal index — postcode-district and property-type-stratified quarterly index built from Land Registry transactions. Largest single accuracy gain in model history: +2.3pp PE10.
v6.6
6 March 2026What changed
Added predicted bathroom count as a dense feature. National predictor providing 99.4% coverage where EPC records lack bathroom data.
v6.3
6 March 2026What changed
Added predicted bedroom count and plot area from EPC records. +1.7pp PE10 combined.
v6.1
5 March 2026What changed
Dynamic model metrics system. Website accuracy stats now driven by quarterly bulk test results, not training metrics.
v6
1 March 2026Headline metrics
| PE10 | MdAPE |
|---|---|
| 60.2% | 7.8% |
What changed
School proximity features (distance to nearest outstanding, good, and any school). Full spatial feature set including flood zones, crime rates, station proximity, and Census 2021 neighbourhood statistics. First version exceeding the Kirchmeyer 50% PE10 minimum.
v5
28 February 2026Headline metrics
| PE10 | MdAPE |
|---|---|
| 59.3% | 7.93% |
What changed
Census 2021 neighbourhood statistics (median household income, employment rate, qualification levels). Income became the single most important feature.
v4
28 February 2026Headline metrics
| PE10 | MdAPE |
|---|---|
| 57.1% | 8.4% |
What changed
Crime rates (total, violent, burglary), station proximity, and flood zone data. First version with full spatial feature set.
v3
1 March 2026Headline metrics
| PE10 | MdAPE |
|---|---|
| 59.4% | 7.9% |
What changed
Previous sale price with HPI temporal adjustment. Single largest feature contribution in model history at this point. PE10 jumped from 45.1% to 59.4% — previous sale price proved to be the most powerful predictor of current value.
v2
February 2026Headline metrics
| PE10 | MdAPE |
|---|---|
| 45.1% | 11.3% |
What changed
First production model. EPC data (floor area, energy rating, construction age), Land Registry transaction history, and basic spatial features.
v1
February 2026Proof of concept. Basic hedonic model. Not deployed to production.