Connecting the data dots: Heather Mattie studies, teaches, and lives connection

In Blog, Unsung Women's Project by Rachel Murray

Welcome back to the Unsung Women’s Project! We’ll be highlighting amazing women in STEM, sharing the stories of all of the incredible, meaningful things women have done in their STEM careers that haven’t gotten the recognition they deserve.


Dr. Mattie’s network science research interests include tie strength estimation and prediction for large-scale social networks and network data imputation. Her data science research interests include methods to limit algorithmic bias and classify subtypes of disease such as diabetes. Dr. Mattie is involved in the diversity and inclusion efforts of the Biostatistics department and enjoys mentoring students.

Could you describe in your own words what your job is, and some of the responsibilities that you have on a daily basis?

I’m an instructor of data science at the Harvard T.H. Chan School of Public Health, and I’m also the executive director of the new Health Data Science Masters program that we have here. I’m also a data science consultant for a healthcare startup in Boston. On a daily basis, I teach two data science courses every semester, and I’m an academic advisor for over 30 students. So, I spend a lot of my day chatting with students, or doing curriculum planning for the program. I also do a lot of analysis and I try to squeeze in my own research when I can, but that’s been pretty difficult.

What kind of research do you do, and what was your dissertation on?

I did my PhD in Biostatistics, but I do a lot of machine learning, which is why I’m in the data science realm. I did my dissertation on network science, which basically focuses on how social connections affect your health. So, for example, if somebody shows up to work with the flu, and you’re in close contact with that person, you’re much more likely to get the flu than someone who works in a different building or even a different department in that same building than that person. It also depends on what kind of relationship you have with that person– friends vs. work acquaintance vs. family, and so on.

So in my dissertation, I studied how this disease would propagate through a population, and which relationships and connections were more important to that propagation, as well as which were less important. I’ve been trying to continue that research a little bit here, and to incorporate machine learning into that.

I also do a little bit of health disparities research, in which I’m trying to figure out how to write machine learning algorithms that aren’t biased against minority populations in terms of healthcare and access to care.

Are you planning on continuing the research you did in your dissertation?

Yes, definitely– technically, 20% of my time at Harvard T.H. Chan is supposed to be research, and at the moment, that doesn’t really happen. What I’m trying to do in the next couple of years is to decrease my teaching load and increase my research load a bit, because it’s just very, very hard to do anything when you’re teaching so much. I really do care about making my lectures as effective as possible, and that takes up a lot of my time.

How did your childhood and academic experiences prepare you for what you do? Growing up, how did you learn?

I’ve always been a math geek. I was very weird in that way, and when you’re little people make fun of you and all of that, but my teachers recognized that in me very quickly. In elementary school, I was put into advanced math courses. I wasn’t advanced in anything else, because I wasn’t that great at anything else, but math was good! That just continued through junior high and high school, where I took all the honors and AP courses in math, which really helped solidify my mathematical foundations.

I thought for a long time that I wanted to be a high school teacher, though, so I went into undergrad thinking I was going to major in education. Then, I found out that to teach high school, you have to major in the subject that you want to teach. So my advisors were like, “Well, what do you want to teach?” And since the answer to that question was math, I switched my major to math and that totally changed my way of thinking and really just opened up a whole new world for me. I then found out that high school students are scary and I didn’t feel like I had enough backbone for that, so I ended up going for a Masters degree in math because I wanted to teach undergraduates.

One of my very last classes for my Masters program was this course on computational methods from molecular biology. We used R and LaTeX to write up our results, and I loved it so much. My professor approached me and asked if I’d ever heard of biostatistics, and I was like, “No, is that really a thing?” And she told me that I should look up PhD programs and keep continuing on this path, and I decided to take her advice and just go for it. I found a bunch of PhD programs in California, which is where I’m from, and then I applied to Penn State and Harvard on more of a whim. I wasn’t initially going to apply there, but my friend convinced me to, since the worst thing that could happen would be that I would just get rejected, and funnily enough, I actually only got into Penn State and Harvard.

When I got here in Boston, I thought I wanted to go into industry, because at that point I was a very low-income person and I couldn’t find a full-time job. So I thought that I’d get my PhD, go into industry, make a ton of money, and it’d be great. But, they make you TA as part of the PhD program, and I was like, “Oh, crap. I actually really do like teaching,” and that swayed me to stay in academia. I think especially for my job, where I have to teach and I have to interact with students all the time, it’s better for everyone involved that I have an approachable personality. My mom is a super bubbly and friendly person, so I think that kind of rubbed off on me. It just turned out that I’m a good fit for this position, because I have that math background, but I’m also someone who can really interact with students and help make them feel comfortable.

Other than growing up a math geek, do you have any stories from when you were younger where you realized you wanted to do math?

In high school, I took a geometry class. My teacher was a woman, and I’ll never forget what she said to us on the first day of class, because it was awful. She said, “Welcome to geometry, girls, don’t worry if you don’t get a good grade in this class because girls aren’t good at math. The boys will probably get the highest grades in this class.” That was early high school, but I remember being so pissed off, thinking, “Watch me get the highest grade in this class, then!” and I actually did. I never said anything to her about it, but that class taught me a couple of things. The first was that I am really passionate about math, and the second one being that I didn’t want anybody telling me that I couldn’t do math, or that I’m not allowed to do it and be good at it. I can be good at it. Even though that was a bad experience, it really instilled in me this kind of fierceness to keep going and not listen to everything that people tell me just because they’re an authority figure, because I know what I’m capable of and what my strengths are.

What’s your superpower?

It’s not actually related to STEM. I think my superpower is inspiring students. I have a lot of patience, and I try to be very kind and understanding all the time, and to remain open-minded. A lot of my students will come into my office crying about all sorts of things, whether it’s curriculum or material or just real life things that happen. Graduate school is tough– I was a grad student, and it wasn’t easy for me, either. So when students come to me with challenges, I really try my hardest to cheer them up and inspire them to keep going, and to understand that it’s not easy for anyone and that it’s going to be okay.

I do a lot of work with minority undergraduates here during the summer, too, which I’m really passionate about. We have a summer program here, so I’ll try to get them excited about graduate school in STEM and I’ll talk to them for hours answering any questions they have, sharing my own experiences, or giving them guidance on all of the different ways they can explore higher education in STEM. Of course, graduate school is really difficult, but I try to inspire my students that they can do it and get through these challenging programs. So, hopefully being a source of inspiration is my superpower.

What is your learning style?

I’m definitely a visual learner. I think with math you sort of have to be, at least to a certain extent. In college, I learned that if I have a big whiteboard in front of me and I draw things out and write things out and actually talk about what I’m doing with someone, the material will sink in better and I’ll start to understand as I’m talking. It doesn’t have to be someone who knows math or anything like that either, just someone I feel comfortable around. I did that with my mom a lot. My mom actually never passed Algebra, but she would listen to me go through presentations I was working on, or just listen to me talk problems through. I learned a lot from that, especially during my PhD, when I would just go into my advisor’s office and write things on the board and talk about them with him. There were a lot of “a-ha” moments doing that, and of course, if you teach something, you start to really gain a deeper knowledge of it, which is also great.

Who were your inspirations growing up?

Growing up, my maternal grandparents were a major source of inspiration for me. They were both such huge believers in education, and they just knew that I was supposed to go to college and graduate school and do something different. My grandfather only had an eighth grade education, and my grandmother had a high school education. But growing up, they would pick me up from school and I would go to their house and finish up my homework because my parents were working. Even when I was in high school and learning things that they had never learned before, they would open the book and sit at the table with me and help me go through it and do my homework. The fact that they took the time to do that for years was so meaningful to me, and I’ll never forget that. The other cool thing was that they were the ones who first taught me about basic addition, subtraction, and multiplication, and they did it by using playing cards. We would play poker and other games, and they’d help me add up all the points. It was a really great and fun introduction to math.

During college, I was going to school more than full-time, and I was working four part-time jobs to just to survive. I would always make time to go over to my grandparents house every week for dinner, though, and my grandfather would give me what he called “mad money,” which was usually like $40 or something, just to have fun with. He’d tell me, “Make sure you have fun with this, because you’re working too hard.” So I could use it to get myself dinner or go out with friends or treat myself to something I couldn’t otherwise afford, and they didn’t have to do that, so they were really big inspirations to me to keep going and keep trying my best because they just believed in me so much.

On the career side, is there anyone who inspires you today professionally?

My dissertation advisor, Dr. JP Onnela, is a huge inspiration to me. He’s a great mentor and super inspiring because he’s one of those people where I feel like he doesn’t have any faults– which I know is definitely not true!– but he’s such a nice person, and he’s smart, and he’s a great researcher, coder, teacher, and writer. I think it’s really amazing that he can be all of these things and still manage to just be nice, because a lot of professors can be very stoic. I’d come into his office, though, and he’d be so patient with me and actually take the time to explain things to me and not get frustrated, which was awesome.

I really try to emulate all of those things in my work as an instructor. I’ll try to copy his style of doing things; like how he does presentations. Obviously, when you work with an advisor in grad school, they edit your dissertation, too, so eventually my writing started to merge a little bit with the way he says some things. I remember occasionally coming up with phrases and thinking, “JP has said this so many times,” but it was never a bad thing, because he’s such a good writer. Really, he’s just a good human and a good academic and I look up to him a lot.

What is the biggest lesson you’ve learned in your career?

I’ve only been out of my PhD for a year and a half, so I think I still have a lot to learn! But as of right now, the biggest lesson for me has been learning to ask for help. I didn’t want to come off as incompetent, so I was scared to ask questions or admit that I was struggling with things. Thankfully, I now know that I work in a very supportive department, so it was really relieving to find out that people are more than happy to help me if I’m honest with them about what I’m dealing with or what sorts of challenges I’m handling. Further than that, I learned that people actually kind of expect you to have issues. My department chair will occasionally stop by my office just to be like, “How are you doing? You surviving? Can I do anything to help?” and that seems so small, but it’s helped so much to take a lot of that pressure off that I have to be perfect or that I can’t make any mistakes. It took me awhile to figure that out, but I’m getting better at it.

What have been some of your challenges, either in your career or personally?

From a personal standpoint, getting a PhD is always really hard. But, being a minority woman in New England, especially one that isn’t from an affluent background and who is attending a school that isn’t particularly diverse… there were a lot of personal challenges there. It was really hard to socialize sometimes, and I had to build my own community around me while I was at Harvard as a student. It took a lot of time for me to do that, though, and at the start of my PhD, I was really lonely, and I think it really contributed to having some Imposter Syndrome at that time. Now, I feel a lot more comfortable as an academic, but that was a real challenge at first.

As far as my career, I didn’t initially realize what was expected of me when I took this job. It was offered to me while I was still a student finishing up my dissertation, and I’m in the same department that I got my PhD from, so I didn’t have to go anywhere– I didn’t have to do a job search, which was awesome, especially since that can be so challenging in academia. My first year here, though, I had to create three new courses with all the curriculum, and I’d only ever been a TA before! I’d never even taught a full course myself, but I was having to learn software myself that I’d never worked with before and then teach it in a week, and it was really jarring, like, “I have no idea why I’m being trusted with this, but I will try my hardest!” There was just a really steep learning curve coming into this new position, and I’m really glad that period of the job is over and it’s getting easier!

You mentioned you have a consulting job as well– what do you do at your consulting job?

I basically do data science research and development for a healthcare startup. What this really means is that I analyze claims data and I try to predict which patients would benefit the most from care management or a similar intervention like that. I work for Wellframe, and they are a company who has built an app that does care management– so it’ll remind you that you have a doctor’s appointment coming up, or remind you to take your medication at certain times or something like that. That’s what care management is at its most simplistic. Right now, I’m figuring out which patients we should email to say, “Hey, you should try this app and see if it helps you.” It involves a lot of the same machine learning techniques that a lot of my other research involves.

Since you’ve talked about your challenges, what do you think your greatest triumphs or career successes are?

I think the biggest triumph is definitely that I get to watch my students succeed. The Master’s program that I help run is super new– this year is only our second year, so we haven’t even seen anyone graduate yet, but our graduate students are getting internships and fellowships. I had a student over the summer emailing me every week just to check in and be like, “Today we did this and built this model, and I felt really smart because I got to use a technique you taught me,” and that feels amazing as a teacher. That’s definitely what I live for, and I’m excited to see where all of my students end up after they actually do graduate.

I teach an introduction to data science course that is open to the entire school and not just our biostats and data science students, which is interesting because we get a lot of students who have never coded before or even thought about how to code, and it’s different than math. So what’s been really awesome with that has been having students come up to me at the end of the semester and tell me how much they learned in the class, and how they’ve actually gotten excited about coding– and I feel like if I can make coding exciting, I’m doing something right! That’s amazing. I don’t know how that happens, but I hope that I’ll keep doing it.

What are the other classes you teach, other than Intro to Data Science?

Other than Intro to Data Science, which I teach in R, I also teach Data Science 2, which is basically deep learning, and I teach that one in Python. I also teach Reproducible Data Science, which is a flipped course, where there’s videos available for it on edX and then I teach the in-class portion. I also teach the Health Data Science capstone course, which is the version of the thesis for our Health Data Science master’s students– it’s more of an applied knowledge course, and I helped lead that.

What does success mean to you?

All I can think of right now is my students! I think success to me is being able to use my skills and abilities to help others succeed. Of course, I’m an academic, so I love knowledge and spreading knowledge, but if I can effectively teach the curriculum to help my students get jobs or internships or accepted into other graduate programs, that’s success to me personally.

What’s something that keeps you up at night?

It’s always the lecture I just gave. I think every teacher will tell you that you can always make your lecture better– it’s never perfect. That will keep me up at night, thinking like, “Oh, I should have said this that way,” or “I didn’t go into detail enough there.” But, I guess it’s just something to keep in mind for the next time I do the lecture, so the worrying is at least a little bit productive!

What’s something that someone who knows you well would be surprised to learn about you?

I used to be very, very shy in high school– I wouldn’t even order a pizza on the phone because I was too afraid to talk to the pizza guy. People don’t believe me because I’m so talkative now and I give so many lectures all the time, but I was definitely the super shy weirdo in high school who was too terrified to speak to anyone.

It was during my PhD when I had to TA that I made that transition to being more outgoing, and it wasn’t easy at all. I was so anxious at first that my legs would just be shaking for the first few months, but luckily no one could really tell. What also really helped was that I was TAing for MDs and lawyers who were really afraid of math, so they thought I was a genius anyway and didn’t really notice if I messed up– I was never aggressively corrected by a student or anything, which would have really shattered my false confidence! But doing that really got me out of my shell, and just having to constantly step out of my comfort zone ended up being really beneficial.

If you had three more hours in a day, how would you spend them?

Definitely baking! I feel like it’s just another way to make people happy and cheer them up. I’ve been doing a lot of baking recently for the holiday season, and I actually gave my entire class a goodie bag of a bunch of cookies recently and they were like, “Oh my god, you know professors don’t do this right?” And I got to feel like the cool professor for a minute there, which was fun.

Other than that, I would probably hang out with my husband a little bit more, since we both don’t have a ton of time, and I’d do yoga and boxing more, since I think those are the exercises that relieve the most stress for me.

Other than what we’ve already covered, what do you geek out about?

Anything that has to do with data science, particularly as it pertains to health! My students are always saying, “Did you hear about this algorithm that predicts this thing more accurately than a doctor?” or stuff like that, and to me, that kind of thing is the coolest. I always want to know more about health data science. I also love math memes and cartoon sketches. It’s kind of silly, but those are really fun for me, too.


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