Most property indices tell you that prices went up or down. We go further: breaking the market into the specific characteristics that drove each move, city by city, year by year.
Pick a city to explore its factor decomposition. Each city has its own hedonic model calibrated to local transaction data.
Standard price indices tell you how much the market moved. Hedonic decomposition tells you why it moved and what drove it.
Energy-efficient homes are increasingly valued by buyers. But how much more are they actually paying, and has that premium widened or narrowed over time? The Energy Rating factor tracks exactly this.
In boom markets, new-build premiums often compress as buyers flee to existing stock. In downturns, they can surge as developers hold prices. The New Build factor isolates this dynamic.
After Covid, buyers in London paid sharply more per extra square metre than before. In New York, the relationship between size and price shifted across boroughs. The Floor Area factor captures these repricing events.
Each city's Index is a constant-quality price index: it reprices a slowly updated basket of homes, so a shift in what sells (bigger homes, cheaper districts) does not move it. The chart compares each city's Index Return since January 2017.
London has data from 1996 but is shown from 2017 here for a clean comparison. The full 30-year London series is on the Trends page.
Divergence reflects prices, not differences in what is being sold.
At each point in time we run a cross-sectional OLS regression of log(price per sqm) on property characteristics using a rolling 3-month window. This gives us the market's implicit price for each attribute: how much extra buyers paid for a new build, for a high energy rating, or for a larger floor area, in that specific window.
Tracking these coefficients over time gives two views. Each factor's Factor Return is the change in its Premium, the price gap between two otherwise identical homes that differ in that one characteristic: a rising House vs Flat Factor Return means buyers pay increasingly more for a house over a flat of the same size. The constant-quality Index splits into the Baseline Market and each factor's Factor Contribution, and Composition explains why the average price actually paid differs from it.
This is the same framework used in equity factor investing (think Fama-French), applied to real estate transactions.
Full methodologyA positive Factor Return means the market paid increasingly more for that characteristic. A negative one means its Premium compressed.
| Factor | What it measures |
|---|---|
| Baseline Market | The part of the Index Return no factor explains |
| Size | How the price per sqm of a larger home compares with a smaller one |
| Recent Build | Premium of recently built homes over older ones |
| Energy Rating | Premium per EPC band |
| Outer vs Inner London | Outer London against an otherwise identical central home |
| Construction Era | Vintage effect: period homes vs. post-war |
Each factor's Factor Return and Transacted Distribution for the selected city: how the market has repriced each characteristic, and how much of it has been selling.
Open FactorsCross-section views: factor correlation matrices, stacked contribution charts, and volatility. Useful for understanding which factors move together and how market regimes shift over time.
Open TrendsHow the regression is specified, how factors are selected, the quality controls applied, and the data sources behind each city. Read this if you want to understand what the model can and cannot capture.
Read methodology