As a basic rule for "which external identifiers are worth covering", I would begin with any national identifiers we have for people (politicians, artists, writers, theologians, scientists, etc), then national identifiers for organizations (government-related, GNP-related businesses, nonprofits, educational institutions, etc), then national identifiers for places (census-defined population centers, battle-scenes, etc)
In my opnion, the question should not be "which identifier has the most coverage" but "which items have the most identifiers" On Thu, Sep 7, 2017 at 9:26 PM, Andrew Gray <and...@generalist.org.uk> wrote: > Hi Marco, > > I guess this depends what you mean by "exhaustive". Exhaustive in that > every Wikidata item has ID X, or exhaustive in that we have every > instance of ID X in Wikidata? > > The first is probably not going to happen, as the vast majority of > external identifiers have a defined scope for what they identify. Some > are pretty broad - VIAF is essentially "everyone who exists in a > library catalogue as an author or subject" - but still have a limit. > We're never really going to reach a situation where there is a single > identifier type that covers everyone, unless we're linking across to > another Wikidata-type comprehensive knowledgebase, and even then we'd > need to ensure we're in a position where they already cover everything > in Wikidata. > > The second can (and has) been done - the largest one I know of offhand > for people is the Oxford DNB (60k items) but for non-people we have > complete coverage of eg Swedish district codes, P1841 (160k items). > It's a bit of a slog to get these completed and then maintained, since > the last 5-10% tend to be more challenging complicated cases, but one > or two determined people can make it happen. And of course it's not > appropriate for many identifiers, as they may issue IDs for things > that we don't intend to have in Wikidata, so we will never completely > cover them. > > I should quickly plug the "expected completeness" property which is > really useful for identifiers - P2429 - as this can quickly show > whether something is a) completely on Wikidata; b) not complete yet > but eventually might be; or c) probably never will be. Not very widely > rolled out yet, though... > > Andrew. > > > On 7 September 2017 at 19:51, Marco Fossati <foss...@spaziodati.eu> wrote: > > Hi everyone, > > > > As a data quality addict, I've been investigating the coverage of > external > > identifiers linked to Wikidata items about people. > > > > Given the numbers on SQID [1] and some SPARQL queries [2, 3], it seems > that > > even the second most used ID (VIAF) only covers *25%* of people items > circa. > > Then, there is a long tail of IDs that are barely used at all. > > > > So here is my question: > > *which external identifiers deserve an effort to achieve exhaustive > > coverage?* > > > > Looking forward to your valuable feedback. > > Cheers, > > > > Marco > > > > [1] https://tools.wmflabs.org/sqid/#/browse?type=properties "Select > > datatype" set to "ExternalId", "Used for class" set to "human Q5" > > [2] total people: http://tinyurl.com/ybvcm5uw > > [3] people with a VIAF link: http://tinyurl.com/ya6dnpr7 > > > > _______________________________________________ > > Wikidata mailing list > > Wikidata@lists.wikimedia.org > > https://lists.wikimedia.org/mailman/listinfo/wikidata > > > > -- > - Andrew Gray > and...@generalist.org.uk > > _______________________________________________ > Wikidata mailing list > Wikidata@lists.wikimedia.org > https://lists.wikimedia.org/mailman/listinfo/wikidata >
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