- Source
- Values: Real Transaction Price of Apartments (Ministry of Land, Infrastructure and Transport) — Ministry of Land, Infrastructure and Transport (국토교통부), via its open API on Korea’s public data portal. District list: the government’s standard administrative code register (dataset). Licence: no restriction on use on both datasets. Window: 2026-05 to 2026-07 (3 months). Retrieved: 2026-09-10.
This is not two sources blended into one ranking. The code register supplies the item set — which districts exist — and every price value comes from the transaction API. The list is needed because the transaction API takes a district code as input. - Four rules fixed before looking at the data
- A three-month window. A single month’s average turns on a handful of sales in districts that trade thinly.
- Two months of reporting lag allowed. Sales must be filed within 30 days of contract, so recent months are incomplete. We measured it: the same district showed 222 sales two months back, 163 the month after, and 72 in the most recent month.
- Cancelled contracts excluded. The source flags them, and those rows are not counted.
- A sample floor of 30 sales. Districts below it are not ranked, but every one is listed with its count at the foot of the index. Left out, not hidden.
That these four were fixed before the data was seen is the point. Moving a threshold after seeing the result is choosing the ranking after seeing it.- Formula, and the column beside it
- The ranking variable is the average transaction price — a plain mean over every sale in the window. But that average follows the mix of apartment sizes that happened to sell: a district where large units traded rises. So the average price per square metre sits in the same row. Where the two orders disagree is the most readable part of the table.
- Why district names are in Korean only
- The source publishes Korean names only. Machine-romanising 214 district names would introduce errors we cannot check — the Subway Index made the same choice for the same reason across 529 stations. We did translate the twelve categories in the Restaurant Index; at this scale we do not.