PhD Student Spotlight: Matthew Casey

Fittingly, Matthew Casey’s “dinner party description” of his research in computational social choice can be framed through the very logistics of dinner party planning.

“Imagine you’re deciding which food to order for a gathering,” said Casey, a second-year PhD student in computer science at Northwestern Engineering. “The attendees provided a list of favored foods, and you need to aggregate their votes into a final selection. My research focuses on designing procedures for voting scenarios to pick the winners in a way that represents everyone’s preferences.”

Advised by Edith Elkind, Ginni Rometty Professor of Computer Science at the McCormick School of Engineering, Casey is a member of the Northwestern CS Theory Group. He focuses on participatory budgeting and multiwinner voting, recently completing a study on the justified representation fairness axiom and guaranteeing proportional representation among an electorate in approval voting.

“The easiest way to select the winning committee of candidates is to pick the set that received the most votes, but this can lead to a situation where a slight majority, say 55 percent, gets all their candidates elected, while the minority gets none,” Casey said. “My work focuses on proving theorems about which voting rules provide proportional representation, and to what degree.”

Prior to joining Northwestern, Casey earned a bachelor’s degree in computer science and mathematics at Northeastern University, where he worked on scheduling algorithms with his mentor Rajmohan Rajaraman.

We asked Casey about his experience as a PhD student at Northwestern, important lessons learned, and his advice for prospective PhD students.

Why did you decide to pursue a PhD in computer science at McCormick?

I was very excited about all the activities going on in the Theory Group. The community is quite close-knit, with a weekly seminar as well as a weekly social hour. In addition, through the Institute for Data, Econometrics, Algorithms, and Learning (IDEAL), there are various collaborations with the statistics, economics, and industrial engineering and management sciences departments at Northwestern, as well as with teams from other Chicagoland universities. I found the potential for collaboration and learning from all these diverse disciplines very enticing.

What are three words you'd use to describe the Northwestern Computer Science community?

Collaborative, action-packed, and friendly.

What are three things you wish you had known before you started your PhD program?

It’s OK to feel lost in your first year; most people do. You are figuring out how PhD programs — and academia more generally — work and what you are passionate about.

Asking for feedback and constructive criticism is crucial to helping you learn faster. There is much less direct assessment of your progress in research than there was in undergrad courses.

It is important to build a life for yourself outside of school. Happiness at home translates to productivity at work.

What are some examples of collaborative or interdisciplinary experiences at Northwestern that have been notably impactful to your research?

Part of my research focuses on participatory budgeting, a democratic process where voters decide how to spend part of a school, city, or state budget. Professor Matt Easterday runs a participatory budgeting process at Northwestern, and he also led an Evanston-wide effort from 2022-23. This was very exciting for me to learn, as my work has been mostly theoretical thus far, and I hope to bridge the gap between theory and practice through a collaboration with that group.

What's next? What are your short- and long-term plans/goals in terms of your career path?

In the short term, I am focusing on learning more about other research going on in my field and continuing work on projects related to fairness and multiwinner voting. Long term, I want to stay in academia and hope to do theoretical work in voting that is practically motivated and actionable by practitioners.

What hobbies/activities do you enjoy? What’s your favorite part about living in Evanston/Chicago?

I am a member of the University’s Billiards Club, attend trivia nights at Bob’s Pizza, and enjoy going to Chicago on the weekend for sporting events, comedy shows, and other entertainment. My favorite part about living in Evanston is being so close to the lake. I love walking by the lake to help clear my head and taking a swim when the weather is warm.

What’s your favorite restaurant in Evanston/Chicago and why?

Blind Faith Cafe is an amazing restaurant in Evanston that serves really good vegetarian/vegan food and desserts.

What advice do you have for prospective Northwestern Computer Science PhD students?

Use the first year of your PhD as a chance to learn as much as you can. Speak with various professors and students about their work and how to be an effective researcher. Read up on different topics, take a variety of courses, and attend departmental seminars. This is an exploratory time where you figure out what your research and career goals are and how to go about achieving them.