Doctorate (PhD)

A student pursuing the Ph.D. degree is expected to exhibit a comprehensive knowledge of a broad cross section of the computer science discipline and to contribute significant new knowledge to the discipline through the research contribution contained in the doctoral dissertation. A PhD student must complete a minimum of 90 credits of graduate study, of which at least 33 must derive from courses. The PhD program is intended to be completed in about five years from entering the graduate program with a BS degree in Computer Science or a related field, or about four years if the student already has an MS degree in Computer Science or a related field. This is possible because students who begin the PhD program already in possession of a Masters may be able to count as many as five courses toward their course requirement (see section Transfer Credits).

To fulfill graduation requirements for the Ph.D. degree, students must satisfy the breadth requirement, adhere to an appropriate credit distribution, enroll in the graduate seminar, comply with the ethics requirement, and complete the major milestones for the degree, including the preliminary exam, research defense and final defense.

 

Breadth Requirements

To encourage Ph.D. graduates to exhibit sufficient breadth of computer science areas, Ph.D. students must take CS courses at the 5000 and 6000 levels that span five (5) different areas. The available courses and areas are listed here.

 

Graduate Seminar Requirement; Graduate School Ethics, Inclusion, and Diversity Requirements

The Graduate School requires that all graduate students satisfy two sets of requirements: one addressing training in Scholarly Ethics and Integrity, and one addressing Inclusion and Diversity. The CS Department also requires students to take a minimum number of instances of CS5944 Graduate Seminar.

Students entering the program in Summer 2019 or after must do the following.

  1. Take some course that makes an explicit part of its syllabus satisfaction of all aspects of both sets of Graduate School requirements (ethics training, and inclusion and diversity training). Within CS, starting with Fall 2019, both CS5014 Research Methods and CS5024 Ethics and Professionalism in Computer Science will include material to satisfy both requirements. CS students may seek approval to satisfy the requirement with another course whose syllabus explicitly addresses both Graduate School requirements.
  2. Take CS5944 Graduate Seminar twice.

Students entering the program prior to Summer 2019 may satisfy the requirements by using the rules listed above, or they may use the following rules. (Please note that if you want to use the rules above, you must have taken the appropriate course in Fall 2019 or after. Earlier instances of the courses do not cover the required training, and so cannot be used.)

  1. Participate in the orientation session offered by the GD. This orientation is done the week before classes start in the Fall and Spring semesters.
  2. Complete the following two courses offered by the Research Division:
  3. Take CS 5944 Graduate Seminar three times.
  4. Students will be required to submit evidence of completion of these milestones in their annual student activity report (see section Annual Evaluation).

 

Credit Distribution Requirements

Category of courses Credit Min Credit Max Notes
CS courses at 4000 level and above 27   All courses must be in CS, but they cannot include CS5974, CS5904, CS5944, CS5994, or CS7994.
CS courses at 4000 level   3 Most CS 4000 courses can be used for graduate credit, except CS4974, CS4944, and CS4994. CS Capstone courses could be used with prior permisison of the instructor.
CS5974 Independent Studies   3  
CS7994 Research and Dissertation 30    
CS courses at 6000 level 6    
Cognate courses 6 6  See the approved list of cognate courses.
Total credits 90    

 

Note: Each of the lines above are individual, distinct, constraints. All constraints must be satisfied. The columns are not meant to “add up”, i.e., 27+30+6+6 is obviously not equal to 90.

Additional credit hours may be taken in any category, but do not count toward degree requirements. Substitutions for degree requirements are allowed only under rare or exceptional circumstances. Requests for substitutions must be made to the GD.

All CS courses must be at the 5000 level or above with at most one 4000-level course included. If a CS 4000 level course is included, it must be from the list of CS 4000 level courses approved for graduate credit. Credits from CS5894 Final Examination and CS5944 Graduate Seminar cannot be used to satisfy any Ph.D. credit requirements. Credits from CS5904 Project and Report, and CS7994 Research and Dissertation cannot be used to satisfy any Ph.D. coursework credit requirements. Observe also the limits on CS5974 in the above credit distribution table. At least two CS 6000 level courses are required and exactly two cognate courses are required. See the department website for a list of approved cognate courses.

 

Advisor and Committee

All graduate students have access to a faculty advisor who can help with both academic advising (i.e., issues related to getting a degree) and career advising. PhD students, and MS students under the thesis option, should select a faculty member to act as their research and course advisor as early as possible in their academic career and definitely by the time their plan of study is due (see Plan of Study). The advisor must be a full-time Virginia Tech faculty position with either a regular, emeritus, or courtesy appointment in the Department of Computer Science, and hold a PhD or equivalent terminal degree.

In place of a single advisor, PhD or MS Thesis students can instead choose two faculty members to serve as co-advisors. In this case, at least one of the co-advisors must be a full-time Virginia Tech faculty position with either a regular, emeritus, or courtesy appointment in the Department of Computer Science, and hold a Ph.D. or equivalent terminal degree. The advisor or co-advisors chair the student’s advisory committee.

The composition of a PhD advisory committee must be designed taking into account the following considerations:

  • The committee must have at least five members (including the advisor or co-advisors).
  • At least four members of the committee must hold a PhD or equivalent terminal degree. Any member without a PhD or equivalent terminal degree must have nationally recognized expertise in their field and have research experience.
  • At least three members must hold tenure track or emeritus positions in the Department of Computer Science.
  • At least one member of the committee must be from outside the university. Note that outside members must be approved by the Graduate School.

A PhD advisory committee must have five members by the time that the preliminary exam is scheduled. However, we will process an initial Plan of Study with only four members of the committee identified.

Ph.D. students who plan to do a thesis but who have not yet selected a research advisor or who need additional academic advising can approach any faculty member on the graduate program committee (GPC) to serve as an interim advisor, and who can serve to provide signatures and other official approvals as required. For most such students, the GD serves as the de-facto interim advisor.

Note: The department is committed to support some of the travel expenses for an external member to visit campus and attend one of the official graduate exams of a dissertation committee. However, the budget for these situations is limited, there are travel authorizations required before the outside member travels, and other approvals. No honorarium can be paid to the visitors, only travel expenses. Consult the GC before making arrangements for travel.

Note: External members must be pre-approved to serve in university PhD committees. This is a step that the student must complete before filing the Plan of Study. The policy on external members is described in the Graduate School Catalog. The form needed is available at the Graduate School forms page.

 

PhD Procedural Milestones

Students seeking a PhD must successfully complete four major milestones: the Qualifying Process, the Preliminary Proposal, the Research Defense, and the Final Defense.

 

Qualifying Process

The PhD qualifying process is completed early in a student's doctoral studies and is the first of four milestones which must be completed successfully to earn the PhD degree. The qualifying process must be completed within 24 months of entering the Ph.D. program. Students who received an M.S. degree in Computer Science at Virginia Tech must complete this stage within 15 months of entering the Ph.D. program. Extensions to these time limits may be negotiated, but extensions are intended to apply to students who take leave from the University, or are part-time students.

It is important to keep in mind that the Ph.D. qualifier is a “process” rather than just an “exam”. It involves two components: excellence in breadth and excellence in depth. Breadth is assessed through classwork achievement. Depth is assessed through a combination of research achievement and the results of a qualifying exam (in the student’s cognizant area of specialty). A Ph.D. student must demonstrate excellence in both breadth and depth to be considered qualified. The qualifying process is completed once the student completes both components. Note that it is meaningless to "qualify on the breadth" component only.

 

Excellence in Breadth

This score is assessed on a binary scale (pass/fail). To pass this requirement, a student needs to take CS courses spanning four areas and receive a GPA of at least 3.5 across these four courses. Only 5000-level and above CS courses eligible to be used on a CS graduate plan of study are considered. At least three 5000-level courses must be included. These courses must be graded on an A-F scale (therefore, CS5974 cannot be included). Transferred courses are not considered. Note that, among all courses taken at Virginia Tech, the student can choose 4 courses of their interest to satisfy this requirement.

 

Excellence in Depth

This score is assessed on a points system using two components: research achievement and a qualifying exam. Each component can provide up to 3 points. Out of the total possible 6 points, a student must obtain 3 points to pass the excellence in depth requirement. Note that it is possible to pass the excellence in depth requirement using only one of the two components (i.e., either research achievement or the qualifying exam).

Research achievement score: This score is assessed by the GD by soliciting input from the faculty regarding a student's research ability. In addition, the student may submit a written description of his or her research achievements. This score will then be assigned based on the individual's research record and the faculty recommendations. Guidelines for scoring:

  • 3: Student has a non-trivial publication record. Traditionally, this is publication of at least one paper in a recognized, peer-reviewed conference or journal, and typically with additional submissions or publications. While this might be for work done prior to entering our program, it is expected that some research work (Independent study, GRA, or major volunteer effort) will have been done here. Alternatively, the student has completed a MS thesis in CS at Virginia Tech, or a peer institution, and has had at least one paper published in a peer reviewed conference or journal. To gain this score, some VT CS faculty member must endorse the student, and be willing to act as PhD advisor.
  • 2: Student has demonstrated research ability through satisfactory performance on an Independent Study project, a graduate research assistantship (GRA) assignment, or an equivalent volume of work on a volunteer basis. This might have been done at another university, and there might be minor publications. To gain this score, some VT CS faculty member must endorse the student, and be willing to act as PhD advisor.
  • 1: Recommendations from faculty who have personal knowledge of a student's research ability, based on class projects, papers, or presentations, indicate that the student is able to do credible research.
  • 0: No evidence of research achievement.
  •  

Qualifying exam score: A PhD qualifying examination committee may be formed in any area recognized by the Department. There is at most one committee per area in a given year and is constituted based on student interest (hence, due to insufficient student interest, some areas might not offer qualifying exams in some years). The examination will be either written or oral (or both), with format and procedures as the examination committee sees fit. Students are normally eligible for only one attempt at the exam.

Guidelines for assessing the qualifying exam score are as follows:

  • 3: Excellent performance, beyond that normally expected or required for a PhD student.
  • 2: Performance appropriate for students preparing to do PhD-level work. Prime factors for assessment include being able to distinguish good work from poor work, and explain why; being able to synthesize the body of work into an assessment of the state-of-the-art on a problem (as indicated by the collection of papers); being able to identify open problems and suggest future work.
  • 1: While the student adequately understands the content of the work, the student is deficient in one or more of the factors listed for assessment under score value of 2. A score of 1 is the minimum necessary for an MS-level pass.
  • 0: Student's performance is such that the committee considers the student unable to do PhD-level work in Computer Science.

Attempting or using a qualifying exam in a given area to get qualified does not “tie” a student to Ph.D. research in that area. For instance, a student might get qualified using scores from the qualifying exam in the HCI area but might opt to pursue a Ph.D. in the area of algorithms and theory. It is presumed that the student’s advisor (and advisory committee) are adequately positioned to judge the suitability of the student’s proficiency to undertake Ph.D. research in a given area and the Preliminary Proposal Exam is an opportunity to ascertain the same.

Since the Ph.D. qualifying exams are offered early in the calendar year, the GD will attempt to assign initial valuations to all who take the exam, and give feedback via email on current standing to those students. If at that point a student has six points, a letter to that effect will be issued automatically. At the end of Spring semester, the GD will attempt to update those valuations based on Spring grades, again issuing a qualification letter if the student is qualified. Aside from immediately after the exam and at the end of Spring semester, evaluation will only be conducted when initiated by the student. There are two cases where a student will initiate an evaluation. (1) If the student determines that he/she can obtain six points without taking the exam, they should contact the GD and provide appropriate documentation to support receiving the points. (2) If at some point after the Spring semester evaluation the student feels he/she has a case for six points, they can contact the GD to do an evaluation. When the qualifier case is clear cut for a given student, the GD will make an immediate determination. Cases that are not clear cut will be referred to the full committee.

As stated earlier, the PhD qualifying examination also serves as one of the two methods whereby an MS coursework-only option student may pass their MS degree final examination.

In consultation with their advisor, once a student completes the requirements for qualification, the student must submit the Request to be Qualified form, available in the forms page of our website.

Constituting the Qualifying Exam Committee: A PhD qualifying examination committee may be formed in any area recognized by the Department . There may only be one committee for any area. A faculty member may serve on at most two committees during a given year. Each year, GD will appoint a chair for each examination committee from among the volunteers for that semester.

The PhD Qualifying Examination is given during a period spanning the end of Fall semester and the start of Spring semester of each year. During early Fall semester, students interested in taking the exam should discuss potential research areas with faculty members so that examination areas of mutual interest can be discovered. Examination committees must post the reading list for their exam by November 1. The exam is normally administered during January and February, with scores reported to GPC by mid February.

Each examination committee will publish a reading list of 10-20 research papers by November 1. It is not a requirement that the papers broadly cover the area, or be "seminal papers" in the area. A list containing papers with results spanning a wide spectrum in regards to quality and relevance is desirable to gauge the student's ability to judge quality and importance of results. The body of work should serve as a good introduction to one or more aspects of the area, but is also selected in part to serve as a vehicle for the exam. For example, a committee giving an exam in algorithms might choose one year to assign a set of papers on NP-complete problems in bioinformatics. The following year, the papers assigned by that committee might be on a completely different topic.

The exam is meant to probe the student's understanding of the content of the papers, the student's ability to synthesize the content into a meaningful understanding of the issues involved, and from there, the student's ability to determine potential "next step" paths of research (based on the papers assigned). In general, the exam is testing the student's ability to critically analyze the material, make judgments regarding the quality and relevance of the results, as well as deriving ideas for future research directions for the specific subtopic addressed in the papers.

At the end of the examination process, the committee must arrive at a scoring in the range 0 to 3 (integer only), and report this score to the GD by the deadline.

 

Preliminary Exam

The Preliminary Proposal Exam is the second of four milestones to be completed by a PhD student. The Preliminary Proposal Exam serves as the University's required Preliminary Exam. The Preliminary Proposal Exam should occur as early as possible after completing the PhD Qualifying Process. It has a recommended deadline of 12-18 months from completion of the Ph.D. qualification process or M.S. degree, whichever comes second. This and subsequent stages requires that the Ph.D. advisor and advisory committee be constituted.

See Scheduling an Exam for details on the mechanics of scheduling the prelim exam with the grad school.

The Preliminary Proposal Exam is an oral presentation and examination expected to last between one and three hours. The actual conduct, content, and scope of the Preliminary Proposal Exam are under the control of the student's advisory committee. However, the intent of the Preliminary Proposal exam is to assess the student's readiness to begin independent research on the proposed problem. In particular, it seeks to answer two questions:

  1. Does the work proposed appear satisfactory to qualify as completing a PhD? This means that the proposed work is not so ambitious as to be implausible for a PhD student, yet is ambitious enough to warrant granting of a PhD if completed.
  2. Is the student adequately prepared to do the proposed work? In particular, does the student have an adequate grasp of the current state-of-the-art in the proposed research area? This is likely to be determined in part by a literature review, which should also be useful to the student at the time of writing the dissertation.

It is expected that, to satisfy these objectives, the student will prepare a document and submit it to the committee sufficiently in advance of the exam that the committee members have adequate time to review it. This document will likely consist of (a) a literature review and discussion of relevant work, and (b) a research plan describing the work to be completed and its significance. To whatever extent is reasonable, it is advisable that the document include a timeline for completion and description of any equipment, supplies, or support necessary for successful completion.

Depending on the will of the committee, the Preliminary Proposal Exam may be limited strictly to a presentation and discussion of the document presented by the student. In addition the committee may, but certainly is not obligated to, chose to ask questions to test the student's background knowledge in the relevant areas of Computer Science. Ideally, the student and advisor will discuss and reach an agreement on the format and scope of the exam well in advance. By passing the student's research proposal, the committee is certifying that, if the student does the stated work in a satisfactory manner, it will prove adequate for a dissertation topic. Note that once the Preliminary Proposal Exam has been completed, there is no necessary requirement that the student's final dissertation adhere to the proposal. The student and committee are free to change the direction of the work as it progresses, based on mutual consent, if they deem that appropriate.

The student is considered to have failed the exam if two or more members of the examination committee give negative votes. If performance on the Preliminary Proposal Exam is unsatisfactory, one full semester must lapse (a minimum of 15 weeks) before the administration of a second examination. The Preliminary Proposal Exam cannot be attempted more than twice.

 

Research Defense

The Research Defense is the third of four milestones that must be completed for the PhD degree. The Research Defense has a recommended deadline of 12-18 months from completion of the Preliminary Proposal Exam, and approximately 3-6 months prior to the Final Defense.

The Research Defense is expected to last one or two hours. The actual conduct, content, and scope of the Research Defense are under the control of the student's advisory committee. The Research Defense should take place once the student has completed most of the work for the dissertation. It is likely that significant writing will yet remain, but no significant problems (other than perhaps mechanical data collection, routine software development, or usability testing) should remain to be solved.

The Research Defense is meant to be an opportunity for the committee to review the key results and verify that a satisfactory body of work appears to have been completed. The committee should understand what has been and what will be accomplished as part of the dissertation, and to agree within itself whether completion of the work as described by the student, or a revision as determined by the committee at the Research Defense, will result in successful completion of the dissertation.

It is expected that the student will prepare a document and submit it to the committee sufficiently in advance of the exam that the committee has sufficient time to review it. If the committee is expected to read and comment on a significant amount of material then it should be given to the committee two weeks in advance of the meeting. The document will likely consist of a review of the proposed work plan (possibly revised since the time of the Preliminary Exam) for the dissertation, and a description of the student's progress towards completing the plan. Key results and their significance should be presented clearly, but briefly. The document should clearly detail what work remains to be done, and the timeframe for its completion. It is not intended that this document be a draft of the dissertation. For some committees, the document might simply be a list of accomplishments and remaining tasks. The student might also submit to the committee copies of papers published or submitted for publication. It is up to the committee to specify how much information it needs to determine if dissertation work is on track.

The Research Defense will typically be the committee's last major opportunity to review the student's progress and work prior to the Final Defense. As such, any major objections or reservations regarding the research plan and progress should be expressed at the Research Defense. Under normal circumstances the expectation is that, if the work completed at the time of the Research Defense is deemed satisfactory, and if the dissertation is completed in the manner specified at the Research Defense, then the result will be deemed satisfactory at the Final Defense.

Note that the Research Defense plays no official role within the University. The Department requires that students pass the Research Defense in a timely manner to remain in good standing. Aside from this, it is up to the student and the committee to determine the next step should a student be considered by the committee to have failed the Research Defense.

 

Final Defense

The last of the four stages for the PhD degree is the Final Defense. It has a recommended deadline of 3-6 months from completion of the Research Defense. During this examination the candidate makes an oral presentation of his or her research work and defends the significance and accuracy of this work in response to questions from the student's committee. The committee, in closed session, determines whether the student has successfully completed the examination.

See Scheduling an Exam for details on the mechanics of scheduling the final exam with the grad school.

If a student fails the final defense, he/she must wait 6 months before attempting the defense again (Graduate School stipulation). The final defense can be attempted at most twice.

As part of the Final Defense process, the student must submit the ETD.

 

MS Along the Way

Successful completion of an M.S. degree in computer science is not a pre-requisite to register as a Ph.D. student at Virginia Tech. Upon entering the graduate program, students are classified as M.S. or Ph.D. based on their stated degree objective.

Students on a Ph.D. track can opt to obtain an M.S. during their course of study, i.e., “along the way”. They may use either the coursework or thesis option. PhD students who have completed the PhD Qualifier Process and who have a valid Plan of Study that satisfies the PhD requirements quite possibly have all the requirements for the MS Coursework. Nevertheless, if a student has cleared the PhD Qualifier Process and has a valid PhD Plan of Study on file, the courses on that PhD plan of study can be used to fulfill the MS Coursework degree requirements. Note however, that each degree requires its own Plan of Study, a second plan of study must be filed for the MS degree. Almost all of the credits in the PhD plan of study can be used for the MS degree. Check with the GC for more specific details.

 

Typical Schedule

The table below shows a typical distribution of courses and other responsibilities over the years that is typical for a student to complete a Phd. Note that this assumes the student starts in the Fall. Also of note is that some of the order of courses shown is a recommendation, not a requirement. For example, whether you take the courses for breadth early in a program of study or later is not of significance.

 

Year Fall Spring
1
  • CS5944 Graduate Seminar (1 cr)
  • CS5xxx (3 cr) (Breadth area 1)
  • CS5xxx (3 cr) (Breadth area 2)
  • CS7994 (credits as needed)

Note: Recommended that students take CS5014: Research Methods in Computer Science course early in their studies.

Note: Student can take up to one CS4xxx. Doing it early in the program is a great way to fill a hole in your background.

Note: Visit several research groups and lab meetings to become acquainted with areas and faculty in department.

  • CS5944 Graduate Seminar (1 cr)
  • CS5xxx (3 cr) (Breadth 3)
  • CS5xxx (3 cr) (Breadth 4)
  • CS7994 (credits as needed)

Note: Identify area of research interest and initiate conversations with possible Academic and Research Advisor.

Note: Submit Student Activity Report in late Spring.

Note: Department evaluates all graduate students on Green Thursday.

Note: If a student is going on internship, there might be other requirements to be met in this semester. For example, international students must have a Plan of Study on file before going on internship. Check with the GC for details.

2
  • CS5944 Graduate Seminar (1 cr)
  • CS xxxx (3 cr)
  • CS xxxx (3 cr)
  • CS7994 (Credits as needed)
  • File a Plan of Study
  • Register for Qualifying Exam
  • CS xxxx (3 cr)
  • CS xxxx (3 cr)
  • CS7994 (Credits as needed)

Note: Complete Qualifying Exam in January

Note: Submit Student Activity Report in late Spring.

Note: Department evaluates all graduate students on Green Thursday.

3
  • CS xxxx (3cr)
  • CS xxxx (3cr)
  • CS7994 (Credits as needed)

Note: Completed Qualifying Process by now

  • CS xxxx (3cr)
  • CS xxxx (3cr)
  • CS7994 (Credits as needed)

Note: Schedule Prelim Exam

Note: Submit Student Activity Report in late Spring.

Note: Department evaluates all graduate students on Green Thursday.

4
  • CS xxxx (3cr)
  • CS xxxx (3cr)
  • CS7994 (Credits as needed)

 

  • CS7994 (Credits as needed)

Note: Student submits Student Activity Report in late Spring.

Note: Department evaluates all graduate students on Green Thursday.

5
  • CS7994 (Credits as needed)

Note: Schedule Research Defense

  • CS7994 (Credits as needed)

Note: Submit Student Activity Report in late Spring.

Note: Department evaluates all graduate students on Green Thursday.

Note: Schedule Final Exam

Note: Apply for Graduation

Note: Conduct Final Exam (defense of thesis)

Note: Submit ETD (no later than 2 weeks after defense date)

Note: Graduate!