The Ph.D. dissertation is normally based on fieldwork or laboratory research, although in special circumstances the department does approve projects on library or other kinds of documentary research. It is, in any event, expected to be an original and significant contribution to scholarship in the student’s chosen field. The supervisor is chosen by the student in the course of preparation of the prospectus, and that choice is subject to approval by the faculty at the time of submission of the prospectus. This person need not be the chair of the student’s advisory committee, or even a member of that committee. In any case two must be faculty at Yale. It is possible, and occasionally necessary for various reasons, formally to change one’s dissertation supervisor.
Following completion of dissertation research, the student is expected to return to Yale and spend another year or more in residence while writing the dissertation.
The formal deadline set by the Graduate School for completion of all requirements for the Ph.D. is six years from matriculation, beyond which students are not permitted to register as such, without the recommendation of their departments and special permission from the Divisional Dean of the Graduate School. Informally, however, students who have not completed their dissertations within six years may remain affiliated with the Department and may continue to work with their supervisors on their dissertations. Over the past two decades, the average time to completion of the dissertation and award of the Ph.D. has been about seven and one-half years. The Graduate School and the Department regard that as excessive and are cooperating in extensive efforts to ensure that most students finish the Ph.D. program in six years or less.