Joseph Chang



In Joseph Chang’s classroom, uncertainty is a given


Statistics teacher Joseph Chang, the 2014 recipient of the Lex Hixon ’63 Prize for Teaching Excellence in the Social Sciences, is happy when students understand that there may be no certain answers to the “big” questions in life, and when the students who are uncertain about their quantitative skills take a chance on a statistics class. He feels rewarded when students can’t help sharing the excitement inspired by his courses, and is always glad when students visit him outside of class.

Courses: “Introductory Statistics,” “Probability and Statistics,” Stochastic Processes,” “Linear Models,” “Advanced Probability,” “Information Theory,” and “Data Analysis”


In his inaugural address, President Peter Salovey described students as one of the “treasures” of Yale. What excites you about teaching Yale undergraduates?

One thing that excites me about teaching undergraduates at Yale is how often I get to teach students who really get excited about the subject themselves. For example, I remember one particular student who told me that she was enjoying the homework questions so much that she couldn’t resist talking about them to her friends at dinner. I suspect she was thinking she might end up eating alone, but still she couldn’t resist sharing the fun that she was having with her fellow students. I find that sort of enthusiasm really rewarding.

Do you learn anything from your students?

I think I learn a lot about teaching from my students every day. When I go into the classroom, just from looking at them, I get an idea what’s interesting and what’s important. When I’m preparing for a class I have a tendency to get worried about some particular point, and if I’m not sure that it’s so clear to me, then I think I better get it really ready to explain to the students. But then when I’m in front of them I see that point is not going to come up and there are other things that I really should be talking about. Yale students are smart and they have good taste, and they help me keep perspective that way.

What drew you to teaching, and what do you find rewarding about it?

What drew me to teaching first of all is that I’ve always liked math, and I sort of understood from early on that to do math for a career one usually teaches. My hero, even as child, was Einstein, and Einstein was a professor so that meant probably I should be a professor. But I think at a deeper level, even as a child, when I learned something and when I really understood it, I sort of felt like I got a new toy, and I wanted to share it and talk about it with somebody. I think for me, teaching is kind of like a favorite hobby, and I enjoy trying to improve at it. I’m looking forward to this summer: There are people at Yale who are experts in new techniques of teaching, and there will be a summer workshop where I’ll be a student learning about these new techniques.

Is there a teacher who particularly inspired you?

I’ve certainly had my share of good teachers but I think what stands out in my mind right now is my colleagues at Yale, in general, and in my department, in particular. At Yale, good teaching is valued; it’s encouraged. And I think it’s quite rare for teaching to be so important at a great research institution like Yale. I look around and I feel fortunate to be in a department that’s filled with people who are really working hard at their teaching. I see people doing great things who I think are at least as deserving of recognition as I am. So that inspires me.

If there’s one thing you’d like your students to learn from you, what would that be?

What I would like them to take away is a general familiarity with uncertainty. I think questions that involve uncertainty are really the interesting and difficult questions in life. If a question really doesn’t involve any uncertainty then in a sense it’s settled — it’s no longer interesting or difficult. So that’s exactly what statistics is: It’s a conceptual framework, and it’s a collection of methods and tools and ways of thinking that help us deal with uncertainty. And I hope the students can keep that with them for the rest of their lives.

What advice would you give a Yale undergraduate about his or her time here?

If I could give one piece of advice to Yale undergraduates it’s that I’d like to see them come to office hours more. There are some students in every class who will come to office hours regularly — the regular customers — and that’s great, but I feel like there are many more students who don’t tend to come to office hours, and I’m not sure exactly why that is. I guess some of them may be feeling too busy; maybe others are thinking that I’m too busy, and that’s not at all the case. I really want students to come during that time, and when they do, I think it’s really helpful to the students. I think that some of my best educational experiences with students have been in office hours. When they come, they find it’s a very relaxed environment. Maybe some students stay away because they feel that they should have prepared: They think maybe they should have prepared a particular question; they should have a good question to ask; they think they should be on top of the material. But that’s certainly not the case. Really, that’s why I’m here, and I hope the students will take advantage of that.

Is there a memorable classroom experience as a teacher you’d like to share?

One example that stands out in my mind is of a particular student who was thinking of taking a class with me, and she was very worried about her math background. She thought it wasn’t enough for the class. In fact, she didn’t have all the prerequisites: The prerequisites were three semesters of calculus, and she only had two semesters of calculus —and that was quite a while ago so her skills were rusty. So she started the class very tentatively, ready to drop it at any moment. But I encouraged her to stay with the class because I could tell that she was really interested in the subject, and I thought that was really the most important thing. As it turned out, she ended up on top of the class, literally with the best score overall in the whole class, and she told me later that she was going on for her master’s degree in statistics at the University of Chicago.