Beside Wikidata, OpenAlex, ORCID and the rest
Wikidata, OpenAlex, Google Scholar, ORCID, the Mathematics Genealogy Project and ProQuest each hold part of a scholar's record, and none of them holds who supervised whom from the theses themselves. This page says what each holds, what it leaves out and what this record adds, with the newest counts.
Wikidata
Wikidata states who advised whom where a volunteer has typed it in, most often for people well enough known to have an item of their own.
Wikidata states 407,549 doctoral advisor links in all. Of the 6,753,639 people in this record, 54,610 have a Wikidata item. The record adds 2,267,820 doctoral supervisions cited from the repositories' own records, and shows them apart from what Wikidata states.
OpenAlex
OpenAlex indexes papers, their authors and their citations. It has no field for who trained whom.
67,288 people in this record have an OpenAlex author record. The record adds the line of advisors above an author and the students below, joined to their papers only where a shared id, or a pair a person has checked, says it is the same person.
Google Scholar
Google Scholar keeps profiles and citation counts. It lists no advisors, no students and no line between them.
The record adds a person's academic family, up and down, from open sources anyone can check.
ORCID
ORCID holds what researchers say of themselves: their posts, their education, their works. It has no place for who supervised whom.
159,515 people in this record carry an ORCID iD given on their thesis record, linked to the supervision that record cites.
The Mathematics Genealogy Project
The classic of the field, built by hand over decades from what people send in, most of it in mathematics.
The record adds every field a repository serves, read again every night, with the source of each link said beside it.
ProQuest
ProQuest's open pages list a thesis's title, school and number; the advisor is inside the document, on its approval page.
The record reads the supervisor from the repository's open record, and for some repositories from the thesis's title page where the record names none.
University repositories
Each repository is a silo, in its own format, its own language and its own spelling of names.
The record reads them into one of 6,016,959 theses, with committees, examiners, opponents and juries beside the supervisors; its doctoral supervisions come from 341 sources in 49 countries.
Where the record stops
6,520,545 of the 6,753,639 people in this record are linked to no other register: for them, this record is the only place their line is drawn. 84.7% of the cited doctoral supervisions have neither person linked to another register yet. Linking them, by the ids their sources give and by pairs a person checks, is the work under way. The coverage page counts it, and the limits say what the record does not know.
Counted 2026-10-24. The full table is on the coverage page.