How Clavy reaches a number, and where it refuses to

A range, never a point

Every estimate is an interval with the central value inside it. The interval comes from the model's own out-of-sample error in that zone (conformal quantiles). It widens when comparables are thin, when the property could only be resolved at a coarser level than its building, when comparables include motivated sellers, and when the model has no fitted error quantiles. Nominal coverage is 80%. Empirical coverage is measured on a holdout for each model version; it is recorded internally and not yet published per zone. The narrowest intervals come from apartments and townhouses in dense urbanisations, where comparables are many and alike; detached villas get the widest, because their comparables are few and unlike each other, and the report says so instead of hiding it. For a wide interval, the comparables and the attribution are the pages to price from.

Attribution you can argue from

Contributions are explicit adjustments against selected comparables (built area, bedrooms, age, and plot and private pool for houses) plus the location level of the urbanisation against its municipality. Terrace and floor adjustments apply only when both the property and the comparable record them; the published data does not yet record them for the property being valued, so they do not currently move the number. A final comparable-evidence row carries what the explicit factors do not explain, so the rows sum to the difference between the mid-point of the range and the municipal baseline. They are never percentages of the answer.

Comparables from the urbanisation, not a radius

On this coast, units inside a gated urbanisation are near-identical and price sharply differently from the street outside. A 1,000 m radius crosses several price regimes. Clavy derives a boundary polygon for each urbanisation from land parcels joined by address and building references, and draws comparables inside it first; only when the urbanisation is thin does it borrow strength from the area, then the municipality — and says so.

Resolution levels

Every fact records the level it was established at. A property resolved at building level says so, and building-level facts are never phrased as unit-level facts.

Three states for every check

Coastal easement, flood and fire zones, protected designations, heritage, planning legality, occupancy, tenancy, title shape and protected-housing status are each carried as present, checked-and-absent, or not assessable. The default is not assessable. Absence of data is never rendered as absence of risk, and none of these is ever turned into an invented discount.

• Present
• Checked, not present
• Not assessable

Illustrative examples, not data for any property.

Market history is observed, not bought

Market figures come from sale listings delivered by Scout, Clavy's listings partner, as observed by Clavy. The listings are imported periodically, not continuously: every market figure shows the date of the data behind it and is marked when it may be out of date. Asking prices are observations, never completed sales.

Where Clavy declines to value

• Bare ownership, protected housing, tourist-let restrictions, occupied or auctioned properties: the listing is flagged and no estimate is produced.
• Land: description and constraints only, no number — land value depends on per-municipality planning we do not hold yet.
• New build: promotion-level analysis (absorption, price ladders), not a unit price.

Data sources and licences

Every data source behind the facts, figures and maps in reports, on property, neighbourhood and town pages and in the 3D town views has an entry in the register below, with its licence, permitted use and the citation we print. A value whose source is not permitted is withheld on public pages, in the property data service and in reports, and a source with no entry is treated as barred. Google Maps is listed as a display-only service: it loads in your browser only after you choose to open the Google view, and nothing from it is stored or used in reports.

Public-record sources

Clavy uses three kinds of public-record source, each under its own terms:

• Parcels, buildings and addresses are Clavy's own transformation of the corresponding DGC INSPIRE datasets, under the DGC INSPIRE licence of 2016.
• Unit details printed in reports (floor, door, stair, use and surface) come from official per-property services. Only non-protected data is used, and it is cited with the date of access.
• Where an authorised CAT bulk file is used, it is used under the DGC bulk-download licence of 2011 and cited with the date of access.

Location names and their hierarchy are curated by Clavy from these sources and keep each source's terms. The public bodies behind them neither participate in nor endorse Clavy. Clavy's outputs are not official certificates and carry no certificative value; the sources and their licences are listed in the legal notice.