Glossary

Every statistical term RealScout uses, defined in plain English. The methodology page carries the full rules behind each one.

Price per square metre (£/m²)

The price a home sold for divided by its internal floor area in square metres. Price per square metre corrects for the size of a home, so different homes and different areas can be compared on one scale. RealScout computes it per sale, then publishes the median across an area.

Median

The middle value of a set: half of matched sales came in above the median, half below. Unlike a mean, a median is barely moved by one extreme sale, which is why it is the headline figure for postcode-district statistics built on small samples.

Mean (average)

The sum of values divided by their count. A mean uses every sale but can be dragged far from the typical sale by a single extreme one, so RealScout publishes the mean alongside the median only where the sample is robust enough for both.

p20–p80 range

The range between the 20th and 80th percentiles of matched sales: the band holding the middle 60% of the market. 20% of sales were cheaper than its low end and 20% dearer than its high end. RealScout uses p20–p80 rather than minimum-to-maximum because the extremes of a small sample are dominated by unusual sales.

Percentile

The share of a sample that falls below a value: a price at the 80th percentile is dearer than 80% of sales. RealScout computes percentiles with the same interpolation rule (type 7) everywhere, in the data pipeline, on the pages and on the map, so the same sample always cuts the same way.

Matched sale

A sale whose address was matched to an Energy Performance Certificate, giving it a floor area and therefore a computable price per square metre. The matched-sale count is the denominator of every £/m² figure and is always printed beside it. Unmatched sales are still counted and listed; only the per-square-metre ratio is unavailable for them.

Transaction count

Every registered sale in an area and window, matched or not. RealScout prints the transaction count beside sale-price statistics, and the matched-sale count beside per-square-metre statistics, because a count shown next to a figure should be that figure’s own denominator.

EPC (Energy Performance Certificate)

The certificate most homes in England & Wales must have when sold or let, recorded in the public Energy Performance of Buildings Register. RealScout uses one field from it: the total internal floor area, recorded to the whole square metre. EPCs have existed since 2008, so older unsold homes may not have one.

Floor area

The total internal usable area of a home in square metres, as measured for its EPC. It excludes garages, unheated porches and spaces with very low ceilings. EPC floor areas are approximate for any single home; across the hundreds of sales behind an area median, their errors largely cancel.

Postcode district (outward code)

The first half of a UK postcode (SW11, M1, LS8), covering typically a few thousand homes. It is RealScout’s main unit of publication: 2,000-plus districts across England & Wales each have their own page. Also called the outward code.

Postcode sector

A postcode district plus the first digit of the second half (SW11 1), covering typically a few streets’ worth of homes. RealScout publishes sector statistics where the sample is large enough, and falls back to the district where it is not.

Tenure (freehold / leasehold)

Whether a sale transferred the property and its land outright (freehold) or a long lease on it (leasehold). Flats are usually leasehold and houses usually freehold, which is why RealScout lets figures be split by tenure: a district where the mix shifts can look like a price change when it is a composition change.

New-build premium

How far the median price per square metre of newly built homes sits above the median for resales in the same area and window. New-builds sell at a premium that fades on resale, so RealScout’s headline figures exclude them and publish the premium separately.

Mix adjustment

Holding an area’s long-run blend of property types constant when computing a price trend. Without it, a quarter that happens to be heavy in flats reads as a price fall. RealScout’s mix-adjusted series blends per-type medians at the area’s own long-run weights; the raw series is always shown too.

CAGR (compound annual growth rate)

The single yearly growth rate that would carry a starting value to an ending value over a period: the honest way to state “+X% a year over 10 years”. RealScout computes it between multi-quarter endpoint averages so one freak quarter cannot rewrite a decade, and never annualises a period under one year.

Real terms (CPIH-adjusted)

A price series restated in today’s money using the Office for National Statistics CPIH inflation index, so a pound in 1995 and a pound today buy the same amount. A market can rise in cash terms and fall in real terms at once; RealScout shows both.

Confidence interval

The range a median is known to, given the size and spread of its own sample: if the sampling were repeated many times, about 95 in 100 intervals built this way would contain the true median. Wider interval, less precise figure. RealScout suppresses the interval entirely rather than publish half of one.

Suppression

Withholding a statistic whose sample is too thin to support it, rather than publishing noise. RealScout’s floors: an area median needs 30 matched sales in its window, ranges need 50, and a postcode-level figure needs at least 3 priced sales before even an indicative median is shown.

Window

The period a statistic is computed over, always stated beside it: “744 matched sales (12 months)”. Busy districts use a 12-month window; thinner areas step up through 24, 36 or 60 months until the sample clears the publication floor, and the page says which window it used.

Registration lag

The 2–8 weeks between a sale completing and HM Land Registry registering it. Because of this lag the newest sales reach the data a month or two after they happen, and the most recent quarters are shown as partial until the register catches up.

Price Paid Data

HM Land Registry’s public record of property sales in England & Wales since 1995: price, date, address, property type, tenure and whether the home was newly built. It is the sale side of every RealScout figure, released monthly under the Open Government Licence.

Open Government Licence (OGL v3.0)

The licence UK public bodies use to release open data. It permits free reuse, including commercially, on condition of attribution. RealScout’s sources and its own published figures all carry OGL v3.0; the required Crown copyright attribution line appears on every page footer.

Outward code

Another name for the postcode district: the first half of a postcode, before the space. SW11’s outward code is SW11. See postcode district.