What are they?
At CMU, your qualifying exams (also known as quals, or The Big Q) are a set of two oral exams that determine whether or not you will be able to continue your PhD. You can find official department information here (https://www.meche.engineering.cmu.edu/_files/documents/handbooks/phdhandbook18.pdf).
The first exam is the Research Exam, which consists of a 10-page report and a 20 minute research presentation based on the research and concepts you have worked on during your first year. After your presentation, a panel of three professors will grill you on your work for 40 min: how you conducted your experiments or modelling, why you made certain decisions, even getting into the basic science of your project. Your goal is to convince them that you understand enough about your project and the research process to be able to excel in your PhD.
The second exam is the Subject Exam, in which you’re given one hour to solve undergraduate-level problems from your selected subject. You’ll have twenty minutes by yourself to think about the problems before you are asked to solve them on the board in front of a panel of professors. They’ll ask you to clarify your process and quiz you on hypotheticals to test the extent of your knowledge of the fundamentals. Essentially, you should be able to fully explain the problem on the fly.
Remember to bring your own whiteboard markers and eraser!
When do I take them?
Research quals generally take place in the first week of the fall semester of your second year at CMU, with the subject exams taking place three weeks later (the exact dates are announced several months beforehand). If you have to retake either exam or if you begin the PhD program in the spring, they will take place at the beginning of the spring semester. Mock quals – practice exams organized by MEGSO and proctored by senior PhD students – take place about one week before your qual. Keep an eye out to sign up for a spot!
The professors will meet to discuss your results on the Friday of the week of subject exam. You will receive a letter notifying you of results on both exams that day; faculty advisors will usually notify their students as well. These letters will be promptly followed by a MEGSO happy hour to mitigate your sorrows or celebrate your joys.
What happens if I fail?
Don’t worry! 40% of people fail at least one of their exams the first time around. If you fail one or both of your exams, you have one opportunity to retake them during the next semester (usually in January). If you fail the second round, you will not be able to continue your PhD, but you will receive a Master’s (Coursework) if you have completed the necessary requirements. But don’t freak out: 98% of people end up passing.
What is it like to take the exam?
“I’m a weird case: I studied math and human movement science in undergrad, so I didn’t even know that mechanical engineering could be broken down into these different categories. My advisors chose my subject exam for me based on my research and what would be most useful for me to learn; if you’re coming in with a mechanical engineering degree, you should pick the exam that plays to your strengths, not necessarily based on your research.
The research exam was a brief presentation of all of the work I had done/planned to do and questions related to that. I had given practice presentations to my lab group and our collaborators so I was prepared to both present and field questions.
Because I had to learn the material from scratch, I started studying for the subject qual over the summer; my labmates took about one month to study. I read through a book (Chris Hertz/older students usually have good sources) and did practice problems I found on the internet, in the book, and from previous quals. I also studied with other people in my year taking the exam. This was the most useful part for me because I was able to formulate the questions I thought they would ask, have practice standing at the board and writing out the solutions, and to compare myself to my peers to see in what areas I needed the most work. For the exam itself, you get a 20-minute period to look at the problem beforehand (bring pencil+paper!!) then you go into the exam room and get grilled for one hour. Make sure you look at all of the problems during the first part because the professors will set the pace so that you can answer everything.”
When/how should I start studying?
Most people start studying the summer before they are scheduled to take the exam (around 3 months in advance). Since the research qual is first, it’s often wise to focus on this at the beginning of your study time, though some people find that they have a lot to catch up on for the subject.
Research Qual: Start making your presentation: organize the work you have done over the past year, and prepare a talk. Delve into the science behind the research, making sure you understand why you made every decision and assumption, what basic science your project is based on, and (it may sound silly) what the ultimate objective of your project is. Leave no stone unturned: if you show them a beautiful model, but don’t know what your boundary conditions are, they won’t forgive you.
Practice with your advisor and with your friends – they’ll have tons of tricky questions you never thought of. Finally, make tons of back-up slides. You will be able to access these during the presentation to show supplementary data, or to help you remember a complicated equation. In the midst of all this, it’s a good idea to get your paper started too. If you are struggling with the organization of your talk, writing may help you work through it.
Subject Qual: First, brush up on the material. Crack open your old undergrad textbook and review the concepts. Next, start running through some practice problems. Take a look at the old exams (available through Chris Hertz) and make sure you’re familiar with the format, so you aren’t surprised by what they might ask. Many students set up study groups with the other students taking their exam or talk to older students who have already passed their quals.
Many advisors organize practice quals for both exams for their students which can be immensely helpful, and MEGSO offers mock quals run by students to supplement or replace this practice.
What material do the exams cover?
Research Qual: The research exam will cover every aspect of the research you present, and every aspect of the fundamentals beneath it. Anything you present is fair game, so if you don’t feel comfortable talking about a certain subject, don’t mention it!
Subject Qual: The subject exam will cover material from of one of seven subjects, design, fluid dynamics, heat transfer, controls, vibrations, solid mechanics, and thermodynamics. The department loves to say that you should demonstrate “a graduate-level understanding of undergraduate material.” Think of it as being able to answer the hardest problems in your undergraduate book (the ones that probably didn’t get assigned when you took the course).