Welcome to the new and improved HAPI report
Three fixed stand-ins have been retired. Each was a shortcut the original design named as a shortcut, and each is now a rule that keeps itself current. Nothing else about the index has moved.
| Element | Until now | In version 2 |
|---|---|---|
| Extreme prices | Everything above £1m excluded outright, as a stand-in for Winsorising | Each region-by-type cell clips its own extremes at the Tukey fences, recomputed monthly, so the threshold moves with the market |
| Stock weights | Survey of English Housing 2003/04, a survey long since replaced | 2021 Census dwelling stock, the basis the ONS uses, re-stated periodically. The fixed-weight method is unchanged |
| Market coverage | Unstated | Measured against HM Land Registry Price Paid Data and published by region: about 83% of completed England and Wales sales |
Four smaller additions come with them: a 95% confidence band around each monthly move, a moving-average series beside the raw index, a time-on-market sample window so long-listed stock is not over-represented, and de-duplication to one record per property across every portal and agent feed.
Read this before comparing figures
Version 2 is a different series from the one published before it, rebased to January 2006 = 100. Read this month against the v2 history in this report, never against a figure from an earlier edition.
Nine elements change in total, each labelled by origin. The full technical account, including measured coverage for every region, is in the companion paper, HAPI version 2, from home.co.uk.