Methodology

How a date gets its status

Confirmed: an official source sets the date, such as an electoral commission, a decree or a law, or we read the official notice ourselves and recorded it with its words and address.

Expected: a source gives a date, usually Wikidata or Wikipedia, but no official source in our data confirms it yet. Due: only a legal deadline is known. No day in our data: our sources give only the month or the year. A vote known only to the month is listed after the dated votes of its month, and one known only to the year after its year's; neither is ever called the next vote.

When two sources disagree, the election keeps its previous status and the two claims are listed on a public page until an official source settles them.

Dates under review

How results are labelled

Provisional results may still change as counting goes on. Final results are the official totals. Certified results are final results an authority has formally certified. Each result says when we read its source.

Where two sources hold the same election, a page shows the national official source first (the House of Commons Library, Die Bundeswahlleiterin), then ParlGov.

Where results come from

ParlGov, a research database, holds national and European Parliament results for 37 countries up to June 2023. It lists parties with at least 1 percent of the vote or 2 seats, so its rows do not add up to the valid votes, and it marks results before 1945 as experimental: we show those but compare them with nothing, and they make no record and no party page. For France it gives the first round's votes and the seats after the second round. Where ParlGov counts an alliance under its first party, the row names the allies. For Japan's 2021 election it gives the seats elected from party lists only, so that page shows no majority line and its largest party is counted by votes.

Parties that stand together and never against each other, with one group in parliament, count as one where a page names the largest party, its lead, the effective number of parties and the Gallagher index: the CDU and the CSU in Germany, Fidesz and the KDNP in Hungary since 2006. Their tables keep a row for each party.

A party carries the name English readers know it by, the title of its English Wikipedia article checked by hand, else ParlGov's English name; a renamed party's tables use the name of their year and its page the newest. A party is named as it is registered, even where the name includes a person's.

France's Ministry of the Interior publishes votes only, grouped by a political label it gives each candidate (a nuance); we compute shares from them and say so under each table.

Turnout

Turnout is the number of people who voted (ballots cast, blank and invalid ballots included) divided by the number of registered voters, as a percent. Its change is the difference in points from the previous election of the same kind in the same country.

Share of the vote

A party's share is its votes divided by the valid votes, as a percent. Where the official source publishes shares we show its own; where it does not (France's Ministry of the Interior publishes votes only) we compute them this way and say so under the table.

Change since the previous election

A party's change is its share now minus its share at the previous election of the same kind in the same country, in percentage points; its seat change is the difference in seats. We compare a party only with itself: the same party in both sources, or the same party linked by our reviewed table of party links. A party that did not stand last time, or that the source does not list, has no change.

Effective number of parties

The effective number of parties (Laakso and Taagepera, 1979) is 1 divided by the sum of the squared shares of the vote (as fractions): two equal parties give 2.0, one party with all the votes gives 1.0. By seats it is the same with shares of the seats. We compute it by votes only when the parties listed cover at least 90 percent of the valid votes, and by seats only when every seat is accounted for.

Gallagher index of disproportionality

The Gallagher index (least squares index, Gallagher 1991) is the square root of half the sum, over the parties, of the squared difference between each party's share of the votes and its share of the seats, in percentage points. 0 means seats follow votes exactly; larger numbers mean less proportional results. We compute it only when the parties listed cover at least 90 percent of the valid votes and every seat is accounted for.

Lead of the largest party

The lead is the share of the party with the most votes minus the share of the party with the second most, in percentage points of the valid votes.

Highest and lowest since

"The highest since 1997" means the highest of every election of the same kind in that country in our data since 1997, the last one that was higher. It is never a record beyond our data: the first year our data holds is always named with it.

Party colours

A party is drawn in the colour its Wikidata entry gives (property P465), as it is. Where that colour has less than 3:1 contrast with the page, its bars and swatches get an outline in a darker shade of the same hue (a lighter one in the dark look) that has it, and its lines are drawn in that shade. A party without a colour, independents and other groups are grey. A colour never carries meaning alone: every bar and line has its party's name and value beside it.

What we never do

We never call a race, forecast a result, publish odds or write text about a result. We never show a result before polls close where the law forbids it. We name no candidate until our assessment of candidate data is adopted.

Corrections

When a new version of an official source changes a number we had already published as final or certified, we update the page and list the change with its old and new value, the date we found it and the reason.

Corrections