The postcode average is a lie

Methodology

Dataset

HM Land Registry Price Paid Data (31.3m transactions)

Window

Jan 2021 – Mar 2026

Sample

2,863 transactions

Filters

• Postcode district OX2 only
• Residential property types (detached, semi-detached, terraced, flat)
• Sale price between £40,000 and £3,000,000 (removes bulk/portfolio transfers and obvious data-entry errors)
• Streets with at least 10 qualifying sales

The exact query

-- Street-level median residential sale price within one postcode
-- district (outcode OX2). Run against price_paid (HM Land Registry).
WITH recent AS (
  SELECT street, price
  FROM price_paid
  WHERE split_part(postcode, ' ', 1) = 'OX2'
    AND date >= '2021-01-01'
    AND property_type IN ('D', 'S', 'T', 'F')  -- detached/semi/terraced/flat
    AND price BETWEEN 40000 AND 3000000         -- drop bulk/portfolio + errors
    AND street IS NOT NULL
)
SELECT
  street,
  count(*)                                            AS sales,
  percentile_cont(0.5) WITHIN GROUP (ORDER BY price)  AS median_price
FROM recent
GROUP BY street
HAVING count(*) >= 10   -- only streets with a defensible sample
ORDER BY median_price DESC;

-- District baseline (the "average" that hides the spread):
--   SELECT percentile_cont(0.5) WITHIN GROUP (ORDER BY price)
--   FROM price_paid WHERE split_part(postcode,' ',1) = 'OX2'
--     AND date >= '2021-01-01' AND property_type IN ('D','S','T','F')
--     AND price BETWEEN 40000 AND 3000000;  -->  570000  (n = 2,863)

Limitations

• Medians use each street's own sample; streets with fewer than 10 qualifying sales since Jan 2021 are excluded, not estimated.
• Map positions are street centroids derived by joining EPC certificates to Ordnance Survey Open UPRN coordinates — an approximate street location, not a per-transaction point.
• HM Land Registry Price Paid excludes some transaction types (e.g. discounted right-to-buy, transfers not for value), so it is a large sample of the market, not a full census.
• A median is a snapshot of what changed hands, not a valuation of every home on the street.