Help:Deprecation

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Deprecated rank.svg

Statements in Wikidata should be ranked as deprecated (and not removed) if they are:

  • superseded (as opposed to "outdated"; see note on 'end date', below)
  • now known to be wrong, but were once thought correct

Background[edit]

The Wikidata web frontend has a different role than the Wikipedia web frontend has. At Wikidata, data users typically do not use the web frontend (they use the Wikidata Query Service (Q20950365) or Wikipedia templates/modules), thus the web frontend is basically a tool for editors only and it is perfectly fine and desirable to have "wrong" or "multiple" values in items, if ranks and sources are properly used. In contrast, Wikipedia readers use the same frontend as Wikipedia editors do, which implies to remove "wrong" values from articles in most cases.

Marking statements as deprecated instead of simply deleting them has several benefits:

  • it allows other users to know not to re-add the value to the item
  • such statements ("known to be untrue", "is not") are necessary in Open-world assumption (Q851949) systems, such as Web Ontology Language (Q826165), by removing "trivial" claims we reduce usage of Wikidata for other purposes
  • it provides a mechanism for representing the evolution of theories and ideas and thereby creates a richer context for understanding human knowledge. This is especially valuable in automated classification systems along with different from (P1889) and similar properties
  • it upholds and establishes the integrity of Wikidata as a secondary knowledge base (that collects and links to references), rather than a primary database of facts. Wikidata simply provides information according to specific sources; those sources may or may not reflect contemporary thought or scientific consensus

At this point it should also be mentioned that deprecated statements are not visible for data users, unless they are explicitly asked for. This applies to the Query Service as well as to Wikipedia parser functions (such as {{#property:}} and {{#statement:}}). Superseded or wrong data, which is correctly tagged with deprecated rank at Wikidata, does therefore not pollute Wikipedia infoboxes, etc.

Reason for deprecation[edit]

A deprecated value should always have a reason for deprecation (P2241) qualifier - see values already used for this (some may be sub-optimal). Some of the potentially useful ones are:

How to apply ranks[edit]

See: Help:Ranking#How to apply ranks.

Outdated statements and 'end date'[edit]

If a value becomes out-of-date, for example:

  • population change measured by a new census
  • spouse no longer applies due to divorce
  • position held no longer applies to due to retirement, or after an election

the value should not be deprecated, but instead an end time qualifier should be added.

Examples[edit]