Epidemiology Field of Study Comprehensive Exam Information

For Students in the Epidemiology Field of Study

Purpose of the Comprehensive Exam

The comprehensive exam is a required milestone for the doctoral program in epidemiology. It is typically undertaken in the fourth term of registration in the PhD program after completion of the core courses, and it must be completed before the end of the fifth term. The purpose of the comprehensive exam is for students to demonstrate their ability to integrate and apply key concepts covered in the core courses to their proposed dissertation topic area. Specifically, it is expected that all students will be able to critically evaluate published and proposed research in their area of research interest, taking into consideration both epidemiology and biostatistics principles. The comprehensive exam also serves as a foundation for the PhD thesis proposal milestone.

Learning Objectives:

  1. To demonstrate competence in the broad concepts, principles, and methods of epidemiology and biostatistics through application, integration, and critical appraisal.
  2. To demonstrate depth of knowledge in methodological issues relevant to the broad dissertation topic area.

Examination Advisory Committee

The comprehensive exam will be administered by the student’s own Examination Advisory Committee which will function as an ad hoc subcommittee of the departmental Comprehensive Exam Committee. Each Examination Advisory Committee will include three faculty members.

The Chair will be appointed by the Comprehensive Exam Committee from the core faculty members in the Department of Epidemiology and Biostatistics who hold Doctoral Supervisory Membership with the School of Graduate and Postdoctoral Studies. The Chair will lead the meetings of Examination Advisory Committee and will provide program-level oversight to ensure that consistent standards are met across comprehensive exams.

The remaining two members will be from the students’ thesis Supervisory Committee and will not include the supervisor(s). Other faculty may be invited if the thesis Supervisory Committee contains fewer members, if specific expertise is needed, or if one of the members is unavailable. It is expected that these two committee members will have substantive and/or methodological expertise relevant to the dissertation topic.

Role of the Thesis Supervisor(s) in the Comprehensive Exam

The Supervisor(s) will participate in the preparation and planning of the comprehensive exam but will not participate in the evaluation. The Supervisor(s) can advise the student in selecting Examination Advisory Committee members, in defining the scope and focus of the exam, and in selecting relevant preparatory reading material. After the meeting when the scope and focus of the exam is finalized, the Supervisor(s) will not be involved in any way in the preparation or evaluation of the exam. In particular, Supervisor(s) cannot read, edit, review, or provide feedback on the student’s comprehensive exam, nor can they discuss the student’s performance with the Examination Advisory Committee members or attempt to influence the exam outcome.

Exam Preparation

Students are expected to demonstrate their ability to apply and integrate key concepts in epidemiology and biostatistics from the core courses (i.e., Foundations of Epidemiology, Clinical Epidemiology, Analytic Epidemiology, Principles of Biostatistics, Multivariable Methods in Biostatistics) to their research area. A careful review of assigned readings from these courses, together with feedback received on assignments and examinations, provides a useful starting point for exam preparation.

Additional suggested readings include:

  • Rothman (2012) Epidemiology: An Introduction, 2nd Edition
  • Guyatt (2014) Users’ Guide to the Medical Literature: A Manual for Evidence-Based Clinical Practice, 3rd Edition
  • Koepsell & Weiss (2014) Epidemiologic Methods: Studying the Occurrence of Illness, 2nd Edition
  • Szklo & Nieto (2019) Epidemiology: Beyond the Basics, 4th Edition
  • Westreich (2019) Epidemiology by Design: A Causal Approach to the Health Sciences
  • Rothman, Greenland, & Lash (2020) Modern Epidemiology, 4th Edition
  • Porta (2014) A Dictionary of Epidemiology, 6th Edition
  • D’Agostino et al. (2005) Introductory Applied Biostatistics
  • Vittinghoff et al. (2012) Regression Methods in Biostatistics


There may also be epidemiological texts that are specific to each student’s research area that may prove useful [e.g., Prince et al. (2020) Practical Psychiatric Epidemiology, 2nd Edition; Oakes & Kaufman (2017) Social Epidemiology, 2nd Edition; Adami et al (2018) Textbook of Cancer Epidemiology, 3rd Edition].

Students are encouraged to organize group study sessions with other doctoral students in their cohort to review and discuss key concepts relevant to each domain, and share examples and applications from their own research area. Example exams from previous years will be made available for review.

Exam Format

The format of the comprehensive exam is a critical methodological appraisal in which students (i) demonstrate their understanding of concepts from the core courses in epidemiology and biostatistics, and (ii) apply these concepts to their broad dissertation research area. Specifically, the student will conduct a critical review of the literature relevant to their proposed research to identify methodological issues, list and explain strengths and weakness of prior research, summarize gaps in knowledge, and outline feasible next steps that could be addressed in the dissertation.

The focus of the methodological appraisal could be a substantive body of research (e.g., dementia) or a methodological body of research (e.g. propensity score matching). In either case, the focus should be in the  general dissertation topic area – the scope of the review may need to be broadened or narrowed to align with the comprehensive exam format. This should be done in consultation with the Supervisor(s) and the Examination  Advisory Committee.

The critical methodological appraisal should begin with a brief background to orient the reader to the general research area, followed by a structured commentary on each of the following domains:

A. Study Design:

Discussion Questions: What have been the common study designs used in this area of research, and why? Have existing study designs limited our acquisition of knowledge in this area of research, and if so, how? How can this be improved?

B. Sampling:

Discussion Questions: How are participants typically identified and sampled in this area of research? Are samples typically limited to one type of setting (e.g., inpatient, outpatient, general population)? Has this limited the generalizability of findings from this area of research, and if so, how? How can this be improved?

C. Measurement:

Discussion Questions: How valid and reliable is the measurement of exposures, outcomes, or other key variables? Has this limited our understanding of this area of research, and if so, how? How can this be improved?

D. Bias:

Discussion Questions: What are some of the key threats to validity in this area of research? Are there specific types of information bias, selection bias, or confounding that are common or unique to this area? Has this limited our understanding of this area of research, and if so, how? How can this be improved?

E. Analysis:

Discussion Questions: What statistical modelling approaches have typically been applied to the analysis of data in this area of research? How are issues of mediation, moderation, and confounding typically handled? What shortcomings related to statistical assumptions, model fit, inferences, and interpretations are seen in the literature? What are some novel approaches that can be used to address these issues?

F. Summary of Gaps in Knowledge and Next Steps:

Provide a brief summary of the key limitations and gaps in knowledge identified by your critical methodological appraisal, and propose areas that can be feasibly addressed in your area of research (or, potentially, in your thesis research) to make a novel contribution to the field.

If the domain is not relevant to a student’s research area, a discussion of why that domain is not relevant can be provided.

One of the stated objectives of the exam is to demonstrate understanding of core concepts in epidemiology and biostatistics. This demonstration of knowledge should be evident throughout the written exam – this can be achieved, for example, by defining core concepts and using explicit examples, such as how a specific type of bias could affect inferences and interpretations.

The five methodological domains (sections A through E) will each be weighted at least 15%, and the summary of gaps in knowledge and next steps (section F) will be 5% of the exam weight. In recognition of the fact that the relative importance of particular methodological domains varies across research topics, the remaining 20% of the exam weight can be distributed across two methodological areas of foci that are of particular relevance for the student’s thesis topic, with no section worth more than 30%. This will be determined in consultation with the Examination Advisory Committee.

The exam should be no more than 7,500 words in length, not including references or any figures, tables, or other appendices (if applicable).

Timeline and Process

Eligibility and Completion

The comprehensive exam process can begin after completion of the core coursework, and once the thesis Supervisory Committee and general dissertation topic have been identified. This exam will typically be written in the Fall term in Year 2 of the PhD program (i.e. Term 4), and should be completed no later than the end of the Winter term in Year 2 (i.e. Term 5). If exceptional circumstances prevent the student from completing the comprehensive exam within this time frame, alternate timelines may be accommodated with approval from the Graduate Chair. Students who completed their MSc in our department, as well as MSc to PhD transfer students, may complete the exam at any point during the first four terms of registration in the PhD program.

Students Alloted Time to Focus

The examination is to be completed in a single term during which students are expected to devote the majority of their time to preparing for and writing the comprehensive exam. Supervisors are asked to respect this and should not expect the student to spend extensive periods of time on research-related activities, particularly during the six-week period that the exam is being written. In addition, the department will aim to limit teaching assistantships to 5 hours per week in the term that the student is writing the comprehensive exam.

Committee Meetings

Early in the term in which the exam will be completed, the student will schedule a meeting of the Examination Advisory Committee to discuss the proposed scope and focus of the comprehensive exam. Students are advised to schedule this meeting as soon as possible, as it can often take several weeks to find a time that works for all examiners. In advance of this meeting, the student will submit a short document (1-2 pages) outlining the proposed research topic and a brief overview of the methodological topics to be discussed within each domain. The student may choose to prepare a short presentation to help guide the discussion, although this is not required. The Supervisor(s) may participate in this process and provide input on the proposed topic and outline.

The Examination Advisory Committee and the Supervisor(s) will meet with the student to provide feedback on the focus and scope of the exam and the proposed discussion topics. The Examination Advisory Committee will advise the student on any additional topics that should be discussed within each of the domains. It is crucial for the committee and the student to have a mutual understanding of the required work, therefore any revisions to the proposed topic and outline must be documented by the student, and a revised proposal submitted to the Examination Advisory Committee within one week. The Examination Advisory Committee will submit a response to the revised proposal within one week. The Chair of the Examination Advisory Committee will ensure that this process and timeline is followed. Once approval has been received from the Examination Advisory Committee, the student submits the comprehensive exam form to the department graduate office, signed by all committee members, the student, and the Supervisor(s).

Writing and Submitting the Examination

The student will have six weeks to complete the exam from the date of approval by the Examination Advisory Committee. The student will complete the exam with minimal input from the Examination Advisory Committee – clarification questions related to scope and focus are permitted. Students may discuss their exams with other students and faculty members not involved in the Examination Advisory Committee (not including their Supervisor(s), but may not circulate drafts of their exam for feedback. Students will submit their completed exam to the Graduate Assistant, who will circulate the exam and evaluation rubric to the Examination Advisory Committee.

Grading the Examination

Each member of the Examination Advisory Committee will independently review the exam and submit a confidential recommendation to the Graduate Chair within two weeks. It is expected that this evaluation will follow the assessment rubric agreed upon by the committee, and feedback will be provided in a similar format to a peer review of a grant or journal article. If there is any disagreement among members of the Examination Advisory Committee on the acceptability of the exam, the examination paper (or relevant sections) will be reviewed and discussed by the departmental Comprehensive Exam Committee, who will make the final determination on the outcome.

Once a decision on the exam outcome is reached, it will be communicated to the student, supervisor(s), and the Examination Advisory Committee by the Graduate Chair.

Overview of Timeline and Registration Process
Term prior to the exam term (typically Year 1 Summer Term)
  • Students who intend to complete the comprehensive exam in the next term will notify the Graduate Assistant by email, noting the thesis Supervisory Committee members and thesis research area.
  • The comprehensive exam is a program milestone, meaning that official registration is not required.
1st month of exam term
  • The department Comprehensive Exam Committee assigns a representative who will Chair the Examination Advisory Committee meeting.
  • The student organizes a meeting with the Examination Advisory Committee to finalize the scope and focus of the comprehensive exam.
  • Once approval of the exam has been received, the student circulates the comprehensive exam form to all committee members describing the agreed-upon scope and focus, as well as the exam deadlines. The signed form is submitted to the Graduate Assistant.
6 weeks following exam approval
  • The student submits the completed exam to the Graduate Assistant.
2 weeks following exam submission
  • The Examination Advisory Committee will independently review the exam and submit a confidential recommendation to the Graduate Chair within two weeks.
  • In the event of a discrepancy between committee members, the Graduate Chair will strike a meeting of the department Comprehensive Exam Committee, who will review the exam and make a final determination on the outcome.
3-4 weeks following exam submission
  • The Graduate Chair will communicate the exam results to the student, supervisor(s), and the Examination Advisory Committee, and sign-off on the comprehensive exam form.
Recording the milestone
  • After receiving a decision of pass on the comprehensive exam form, the Graduate Assistant will process the milestone as complete, which will be reflected on the student transcript.

 

Examination Outcomes

The exam will be graded as (i) pass, (ii) revise and resubmit, or (iii) fail, based on application of the assessment rubric, which will be made available to students writing the exam.

i. Pass: A decision of pass indicates that the student demonstrates competency in the application and integration of core concepts in epidemiology and biostatistics to their area of research. The Examination Advisory Committee may have additional feedback or suggestions for revisions, which can be incorporated into the thesis proposal, the thesis, or other reports or manuscripts that evolve from the comprehensive exam. Students are strongly encouraged to schedule a follow-up meeting with the Examination Advisory Committee and their supervisor(s) to discuss the feedback and address any outstanding questions or areas in need of clarification.
ii. Follow-up: If the Examination Advisory Committee identifies deficiencies that are limited to a particular area or topic, the student will receive one or more follow-up question(s) that provide an opportunity for targeted remediation of the identified area(s). The response to the follow-up question(s) should typically be submitted within 2 weeks.
iii. Fail: A decision of failure will be made in situations where there are widespread deficiencies across domains of the exam, or if the student’s response from (ii) does not meet expectations after resubmission. In the event of a failure, the student will be provided with written feedback on the exam and areas of deficiency. The Examination Advisory Committee will meet with the student to develop a remediation plan, which may include suggested readings and/or additional coursework. The timeline will depend on the extent of remediation required; however, the timeline should be a minimum of 6 weeks to allow sufficient review of deficient areas, and could be up to one term in the event that additional coursework is recommended. The student will complete the remediation plan and submit a revised exam addressing the identified issues, which will be reviewed by the Examination Advisory Committee using the same process outlined previously. If the exam is still considered to be deficient in one or more areas after the second attempt, the student will be asked to withdraw from the program.


Please note that all comprehensive exams will be submitted to TurnItIn to identify plagiarism. Students who are unclear about the precise definition of plagiarism are strongly encouraged to review the university guidelines on cheating, plagiarism, and other scholastic offences, available at https://uwo.ca/ombuds//get-help.html. Western University's Academic policy, Scholastic Discipline for Graduate Students, is available here:  https://www.uwo.ca/univsec/pdf/academic_policies/appeals/scholastic_discipline_grad.pdf. Plagiarism is a serious academic offence that could result in dismissal from the program.