How Housing Market Insights chooses sources and checks figures

Where the figures come from

For each country, Insights keeps a register of the organisations that publish housing figures: statistics offices, central banks, land registries, government ministries and major property portals, plus the international bodies that publish figures for many countries at once, such as the World Bank, the IMF, the OECD, Eurostat and the Bank for International Settlements.

New sources are looked for every night, including searches in each country's own languages. A source found this way is a candidate: nothing it publishes is shown until it has been approved and its figures have passed every check below.

How a source is approved, automatically

Every source gets a trust score from 0 to 100. The score is built from five things: what kind of organisation it is, how often its figures agree with sources that are already trusted, how up to date it is, how structured its data is, and its track record over time.

A high score approves the source automatically and a low score rejects it. Sources in between go on probation. No person approves or rejects a source by hand, and every decision is recorded with the score and the reasons behind it.

Official government websites on each country's own list are approved automatically, as long as they publish at least one housing metric and their figures do not disagree with trusted sources. Approval only means a source may be used: its figures still have to be confirmed by a second, independent source before they are shown.

Where a source's identity is unclear, an automated check looks at who owns the website, whether it cites official data, whether it explains its methods and whether reputable sites refer to it.

Probation

A source on probation is collected, but none of its figures is shown. For several weeks its figures are compared with those of trusted sources.

If they agree often enough, the source is promoted and its figures can be published. If they do not, the source is dropped. Both happen automatically, and the source's record is kept either way.

Confirmation: two independent sources, or the official publisher

A figure is published when at least two independent sources agree on it, within a tolerance set for each metric. Two websites that republish the same organisation's figure count as one source, not two. The one exception is a figure from the official publisher of that country's own statistic, such as a central bank's policy rate or a national statistics office's index. It can be published on its own, with the publisher named, as long as no other approved source disagrees with it. It is then marked as a single official source.

The figure shown is the one published by the most trusted source whose terms allow it to be shown, exactly as that source published it. Figures are never averaged, because an average would be a number nobody published.

Each new figure is also checked against the history of the same series. A figure that jumps far outside its history, or on which the sources disagree, is held back and not shown until it has been checked again.

Whose figures are shown

A source's figures are shown only when its terms of use allow reuse with attribution. The organisation is then named and linked next to every figure, together with a link to the page or file the figure was read from.

Sources whose terms do not allow this, or do not say, are used only to check other sources' figures. Their figures are never shown on these pages.

How often figures update

Approved sources are checked for new figures several times a day, and new figures are checked the same day. A figure changes only when its publisher releases a new one, so most figures change monthly or quarterly.

Each figure shows the period it covers and, where the publisher states it, the date it was released. When a publisher revises a figure, the revision replaces the earlier one on the page and the earlier one is kept in the record.

Aggregated statistics only

Only aggregated statistics are published: figures for a country, region or city. Nothing about an individual property, listing or person is ever shown. Figures from Housing Market Group's own platforms are left out where too few listings or searches stand behind them to protect privacy.

Articles

Insights writes original articles around published figures, adding Housing Market Group's comparisons across countries and over time. Every number in an article comes from figures that passed the checks above, and every article names and links its sources.

Each article is checked for originality against the source material before it is published, and is rewritten if it is too close. Articles stay on this site permanently. If a figure in an article is corrected, the correction is noted on the article.

A record of every decision

Every automated decision, from approving a source to publishing a figure, is written to a permanent record with the inputs, the score and the rule that applied. Sources and figures are never deleted; their status changes instead.

Found a problem?

If you think a figure is wrong, write to support@housingmarketgroup.com with the page address. We check it against the source and correct the page if needed.