Sources and checking
Every event on this site links to the pages it was checked against. This page explains how events are chosen, how they are checked, and how sure we are about each one.
How events are chosen
For each year we gathered several thousand candidate events from Wikipedia and Wikidata, scored them by how widely known they are today (how many language editions of Wikipedia cover them, and how often those articles are read), and set aside a share for places outside Europe and North America so the pages are not only about the West. Little-known births, deaths and releases were dropped by rule. Where two rows described the same moment, we kept one. That leaves about 500 events a year.
How events are checked
- Facts first, then words. The facts of each event (date, place, who, what) were drafted from a source we opened; the summary was written afterwards in fresh words, never copied. A scan blocks any run of eight or more words shared with the source.
- A separate checker. A checker that did not write the event read its full article, and for risky claims (numbers, records, firsts, the exact day of a battle, treaty or premiere) the French or German Wikipedia as well.
- Calendars. Russia used the Julian calendar until February 1918 and the Ottoman Empire its own Rumi calendar. Every date here is Gregorian; where a country used another calendar, the original is in the notes.
- Disagreements are written down, not settled quietly. When sources give different days or numbers, the notes record both and the confidence is lowered.
- Random audits. Each year was audited on a random sample of 150 events by a reviewer that built nothing. The pass mark is 95%; every finding was then repaired.
| Year | Events | Audit score |
|---|---|---|
| 1912 | 490 | 98.0% |
| 1913 | 494 | 96.7% |
| 1914 | 497 | 99.3% |
| 1915 | 497 | 97.3% |
| 1916 | 492 | 97.3% |
| 1917 | 494 | 96.7% |
| 1918 | 496 | 98.0% |
| 1919 | 499 | 99.3% |
How sure we are
High confidence (2,292 events): the sources agree and the checker confirmed the facts. Medium confidence (1,569): the event rests on one source family, often English Wikipedia alone, or one detail is uncertain. Low confidence (98): the sources disagree or are thin on part of the story; the notes say where.
Source families
We record which family each source belongs to, so that sources can be swapped later if needed.
| Family | Events citing it | Links |
|---|---|---|
| Wikimedia (Wikipedia in several languages, Wikidata) | 3,958 | 8,807 |
| Specialist sites and datasets | 111 | 128 |
| Government and official bodies | 42 | 44 |
| Scholarly publications | 5 | 5 |
Most-cited: Wikipedia (4,209), Wikidata (3,858), German Wikipedia (256), French Wikipedia (116), Spanish Wikipedia (62), Russian Wikipedia (51), Portuguese Wikipedia (40), Italian Wikipedia (36). No event on this site cites Encyclopaedia Britannica; a check blocks it from every build.
AI and editing
Summaries drafted with AI and reviewed by an editor. AI helped gather candidates, draft facts and summaries, and run the checks; the separate checkers and auditors are also AI models working from the opened sources, and an editor reviews the results. Mistakes are still possible. The source links on every event are there so you can check for yourself.
Known limits
- About a third of Wikipedia links point to the exact revision that was checked; the rest point to the live article, which may have changed since.
- Translations of one article in other languages are not counted as independent sources.
- The ranking by how widely known an event is today favours events with many Wikipedia articles, which still leans towards Europe and North America.