Data Methodology | Property Market Data

Data Sources

Property Market Data draws from four primary categories of data, each selected for coverage, reliability and update frequency.

Transactional

HM Land Registry

Every residential property transaction in England and Wales since 1995. Price Paid Data (open licence), updated monthly. Over 28 million records. The definitive source for actual sale prices, property types and transaction dates.

Market Analytics

PropertyData.co.uk

Licensed commercial dataset providing current asking prices, days on market, price reductions, stock levels and demand indicators. Covers active listings across major UK portals. Updated daily.

Price Indices

UK House Price Index

The official ONS and Land Registry house price index, published monthly at national, regional, county and local authority level. Used for time-adjusting historical comparables to present-day values.

Building Data

EPC Register

Energy Performance Certificate data for domestic properties, including floor area (square metres), energy ratings and property characteristics. Published by DLUHC under open licence.

Supplementary Sources

ONS Census 2021 for demographic and household composition profiles
Ofsted school inspection data for education quality indicators
Council tax band distributions for area wealth profiling
Live on-market tracking for current stock and pricing movements

How We Calculate

Raw data is processed through a structured pipeline before it reaches any report. Each stage is designed to reduce noise, account for time effects and reflect genuine local market conditions rather than regional averages.

1. Collection and validation

Data is ingested daily from source APIs. Duplicate transactions are de-duplicated. Records are validated against expected ranges - anomalous entries (such as zero-value transactions or clearly erroneous prices) are flagged and excluded.

2. Geographic assignment

Each property is matched to its local area using postcode-level geocoding. Market statistics are calculated at three tiers: immediate locality, surrounding area and wider district, giving a layered view of the market rather than a single blunt average.

3. Time adjustment

Historical comparable sales are adjusted to present-day values using the UK House Price Index at the most granular level available. A property that sold 18 months ago is not presented at its original price - it is adjusted to reflect subsequent market movement.

4. Size normalisation

Where floor area data is available from EPC records, comparable properties are filtered and analysed on a price-per-square-foot basis. This controls for the most significant variable in property pricing and produces more meaningful comparisons than headline prices alone.

5. Market Strength Index

A composite indicator combining demand signals, stock levels, sale-to-list ratios and price momentum. Calculated at both local and (for higher-value properties) luxury market tiers. This dual-layer approach prevents London-driven national sentiment from distorting a rural Norfolk assessment.

6. Report generation

Processed data feeds into structured report templates. AI-assisted narrative sections interpret the numbers in plain language, but every claim is anchored to a specific data point. The underlying statistics are always available alongside the commentary.

Asking Prices vs Sold Prices

Property Market Data tracks both asking prices (what sellers hope to achieve) and sold prices (what buyers actually paid). These are distinct datasets with different characteristics.

Asking prices are drawn from live market listings. They reflect current seller expectations and market positioning, but they are not transaction evidence.
Sold prices come from Land Registry records. They are verified, legally recorded transaction values - but they lag the market by 2-4 months due to the time between sale agreement and registration.

Where our reports present both, they are always clearly labelled. Valuation analysis weights sold price evidence more heavily, while market commentary uses asking price trends to identify emerging movement.

Update Frequency

Different datasets refresh at different intervals. This table shows the typical update cycle for each primary source.

Dataset	Frequency	Typical Lag
Land Registry transactions	Daily	2-4 months from sale to registration
On-market listings and asking prices	Daily	Same day
UK House Price Index	Monthly	Published ~6 weeks after reference month
EPC data	Daily	Typically within days of lodgement
Location market reports	Monthly	Regenerated with latest available data
District-level aggregates	Monthly	Recalculated after Land Registry refresh

Data vs Interpretation

An important distinction

Property Market Data provides the underlying intelligence: transaction records, market statistics, pricing analytics and trend data. When an estate agent uses this platform to produce a property report or market commentary, any strategic advice, pricing recommendations or market opinions expressed are theirs, not ours. The data informs; the agent interprets.

Each client estate agent applies their own local expertise, property knowledge and professional judgement when translating market data into advice for their clients. Two agents analysing the same dataset for the same property may reasonably reach different conclusions, because they bring different experience and market perspective.

This is by design. Property Market Data exists to give agents the strongest possible evidence base. What they do with that evidence - how they interpret it, weight it and present it - is the value they add.

Quality Standards and Known Limitations

We take accuracy seriously, and we are transparent about the boundaries of what data can tell you.

What we do

Validate all ingested data against expected ranges
De-duplicate records across overlapping sources
Time-adjust historical prices to present-day values
Size-filter comparables to avoid misleading cross-type comparisons
Refresh datasets on published schedules rather than on demand

Known limitations

Land Registry data does not capture private sales, off-market transactions, or sales at auction where the price is not publicly recorded in the standard feed
EPC floor area data is not available for all properties, particularly older homes that have never been marketed or let
On-market data depends on properties being listed on major portals. Pocket listings, private sales and off-market deals are not captured
The UK HPI is published with a lag, meaning the most recent 6-8 weeks of market movement may not yet be reflected in time-adjusted figures
Rural and coastal areas with low transaction volumes produce wider confidence intervals than urban markets with high turnover