What the record does not know
The record holds what its sources hold. Many theses name no supervisor, many state no level, one person spelled two ways stays two until an identifier joins them, and some countries are barely reached. Each gap is shown where it falls, with the reason where the record knows it, and never filled by a guess.
Where the record stops
The record holds what its sources hold, and no more. A person with no students in the record may have had many; a line that ends may go on in a repository the record does not read, or in one whose records do not say who supervised. So a branch that stops because the data stops is marked so. On a sheet, a short bar under or over a person's mark says the record holds nobody past them on that side, and their card says the record stops there, which is not evidence that there is no one. A missing source is not an absent student.
Each gap below is shown where it falls and is never filled by a guess: no supervisor is supplied because a name is likely, no level because a degree is likely, and no two people are joined because their names agree.
Theses that name no supervisor
Many thesis records name their author and no supervisor. Some repositories never record one; some record one in a field their export leaves out; some print the name only on the thesis's title page. Such a thesis is still held: it is a record of authorship, its author may supervise others later, and its page says plainly that the record names no supervisor for it.
Where a thesis is linked to no supervisor, the record keeps the reason, and the thesis's page says it in a sentence:
- It names the author alone
- the record names no one but the author.
- It names others, none as supervisor
- it names people besides the author, none of them in a role that makes a supervision.
- It names a committee or examiners
- it names a committee, examiners or a jury and no supervisor; they are drawn beside the lineage, not in it.
- It names no author
- so there is no student to link to a supervisor.
- It names the author as the supervisor
- the name in the supervisor's place is the author's own, typed again or shared with someone of the same name, and no one is linked to themselves.
- It points only to a first referee
- in some German repositories the first referee is most often the supervisor; that link is drawn as suggested, not recorded, and is not counted.
- It is already linked
- the same supervision came first from an earlier record of the same repository, so the link is drawn once. This one is no gap.
The reason matters to a reader. It says whether the gap is the source's or a field the record does not yet read, and so where to look next. Counted by source, the reasons are also how the work of closing gaps is chosen: a repository whose theses all name their author alone wants a new way in, and one whose supervisors sit in a field not yet read wants a new reading.
How such gaps are closed
A supervisor missing from a repository's record is often written somewhere else the record can read. It is lent to the thesis from there only where the thesis's own record names no supervisor, and only once the reading has been checked on a sample of theses against what their own pages say.
- The title page
- Many theses print the supervisor on their first page. Where a repository serves the text it took from a thesis's file, the record reads its first lines for the supervisor's label, as at the Technical University of Liberec, whose title pages name the "Vedoucí práce".
- The thesis's own page
- Some schools publish a page for each thesis that names its supervisor where the repository's record does not, and the record reads that page once.
- A national register
- Portugal's register of theses names supervisors some universities' repositories leave out. For the University of Porto, the University of Minho and ISCTE, the record lends the register's supervisors to the repository's record of the same thesis, found by the address the register gives it there.
- The thesis's text
- Where nothing else names the supervisor, a language model may read the thesis's own text for the name its title page or acknowledgements give. The finding is a kind of evidence of its own and enters the record only through a check, as where AI is used explains.
Theses of unknown level
A thesis record should say what degree it was written for, and many do not. Some formats have no field for it; some repositories type every thesis "Thesis"; and some words do not decide it: "Dissertation" names a doctoral dissertation at most American universities and a master's thesis at some. Where the level cannot be read from what the source states, the record says the level is unknown.
A thesis of unknown level is not counted as a doctorate. The lineage is the line of doctoral supervision: a sheet walks it, and the coverage page and the record's picks count it. A thesis of unknown level is drawn only when a reader asks to see the theses below the doctorate, with the master's and bachelor's theses, and is counted in none of the doctoral figures. Counting it would make many a master's student someone's doctoral student.
Counted 2026-10-20. The full table is on the coverage page.
Namesakes and spellings
A name is not a person. Within one source, two people who share a name exactly are one entry, since nothing in the records tells them apart; across sources, one person spelled two ways, or recorded by two repositories, stays two people until a shared identifier such as an ORCID iD, or a join checked on a sample, says they are one. So a person's students may be split between two entries, and two people's between one. Who is who explains how people are told apart and joined.
Countries and fields reached thinly
The record reaches a country only through sources it can read, and some countries are reached through one repository, or a few theses, or not at all. The chart draws every country the newest count records, the most first, so the long tail is seen; a country in it holds as many supervisions as the record has read, not as many as its universities awarded.
Counted 2026-10-20. The full table is on the coverage page.
Time is reached thinly too: 89,922 of the 2,210,895 cited doctoral supervisions (4.1%) are of theses written before 1990.
The record does not yet count its theses by discipline, so a thinly reached field cannot be shown here as a thinly reached country is. Some fields leave few theses at all: a physician is trained through residency and fellowship rather than a thesis, and no source the record reads says who trained one. For a physician with papers and no thesis, the card shows the degree, school and year Medicare's public list of clinicians gives, as unconfirmed.
Many sources are known and not read: some refuse access, some offer web pages and no data a program can read, and some serve records that name no supervisor. The first page lists them by state under "Where the record stops", and where the data comes from says how sources are found and read.
Closing a gap yourself
A reader who knows what the record lacks can say so. Report a missing advisor: the report is checked against the record at once, and where the supervision is not there, the page says how to record it on Wikidata, citing where it is written; Wikidata is one of the record's sources, and the link shows on the sheet after the next update. Report a missing work: it is checked against the person's works and kept, so the repository that holds the work can be found and read.
Neither report is drawn as a link by itself: a link rests on a source a reader can open. To point the record to a repository it does not read, write to academicancestry@proton.me.