What Does a Public Health Scientist Do?

How do you introduce yourself, scientifically? 

My name is Daniel Arias and I am a public health scientist specializing in health systems and health financing. I think the inclusion of ‘scientist’ after public health is valuable—our work is grounded in theory, relies on systematic observation of the world, and is conducted with methodological rigor, yet many researchers who work in public health have to push for recognition as scientists. 

What are the implications or broader impacts of your work? 

By nature, the things that we do as public health scientists touch on peoples’ lives, including their health, experiences, and welfare. Ironically, if public health is going well, people may not take any notice—the absence, though, of effective public health is all-too prominent. It is important to recognize, though, that public health interventions can encroach on peoples’ lives. Many important discussions revolve around what we, as people who want to intervene to protect the public’s health, should have the power to do, have the duty to do, and have an obligation not to do. Because ultimately, we are expressing our values through public health—how do we balance individual liberties and choices with the public good and the collective welfare?

What does your data look like? What information do you gather about the world? 

Public health is exciting because data can take many forms, and data from unexpected sources can sometimes show really surprising impacts of interventions! In the past, I’ve collected qualitative data by interviewing faith healers in Ghana (Figure 1). In that case, we were curious about potential ways to overcome service capacity gaps in the mental health care system (see photo below). We wanted to explore the potential for linkages between medical care providers and religious healers to try to address peoples’ mental health needs in a more holistic way. Right now, my research is more quantitative. I am currently tracking national indicators of development and welfare to find predictors of good or bad population-level mental health. In my experience, both qualitative and quantitative data can give you useful information. For instance, qualitative interviews often provide insight into why people are behaving in a particular way; the ‘why’ of certain behaviors can help you interpret quantitative data and draw connections that are relevant to policy-making. 

Figure 1: Nurses review patient records at the Accra Psychiatric Hospital in Ghana. Source: Daniel Arias.

What does data collection typically look like for you? 

Most of the data I work with right now has been collected by somebody else, and I am doing secondary analysis. My impression is that public health researchers approach data collection in one of two ways, drawing from epidemiology and econometrics, respectively. Some researchers start with a question and then collect data to try and answer it (like in an experimental trial). Others start with large sets of data that already exist, such as micro-data on household health behaviors or tax returns, and then explore what questions can be answered using these data to draw out causal inferences. I think it’s valuable to have both approaches in your head when thinking about the kinds of questions you can answer: What questions do I have and what data do I need to collect to answer those questions? What questions can I answer with data that is already available? 

What happens after you collect your data, and what do you hope it reveals?

The experience of data analysis varies a lot based on the purpose of the work, but the main goal of observational and experimental studies in public health is to draw conclusions about causality. Data can reveal associations, for example, between an exposure, like smoking, and an outcome, like lung cancer. But we want to be able to say whether smoking causes lung cancer: does the exposure cause the outcome? While there are many factors that strengthen causal interpretations, there is no universal checklist of criteria you need to meet to establish causal relationships. Instead, we have to use expert knowledge to check our assumptions, find sources of bias, and understand our data in order to conclude that one factor causes a specific outcome. 

What makes a public health scientist different from other scientists? 

One difference between us and other researchers is that we often have to defend ourselves as scientists. Many science foundations, like the National Science Foundation (NSF), don’t award grants for public health research. I think this is a missed opportunity to leverage science for the public good and unhelpfully pits so-called basic vs. applied research against one another. The National Institutes of Health (NIH), for example, has historically focused on supporting the biomedical sciences—despite its mission also encompassing the application of knowledge to improve human life and longevity. Biomedical sciences are exceptionally valuable, but I’ll note that when we look at the reasons that people are living longer and healthier lives—and at the current threats to those gains—public health, sanitation, and hygiene may outweigh biomedical advances in terms of impact.

One example is cancer: a lot of current cancer research aims to develop new treatments, which are sorely needed. At the same time, much of the global burden of cancer can be averted through changes in diet, environment, and lifestyle—yet the cancers that emerge from behavioral risk factors get relatively less funding. Some argue that this is correct, as these cancers are caused by personal choices, like smoking and drinking. But if our goal is to improve population health, we have to adopt a broader perspective and theory of disease, one that embraces social responsibilities and the social determinants of health. A reason people get sick is not just that they happened to not have a sufficient diet or were living in a dangerous environment, but that there are factors forcing them into deprivation and constrained opportunities. If people aren’t making good choices about their health, it might be that they don’t have good choices available to them.

Along that line, I think public health scientists are distinguished, too, by the reflexivity of what we do. At its core, we are concerned about people’s health, not merely because we are intellectually curious, but because we want to do something about it. Intervention is directly in mind. 

Is there a common misconception about your field? 

An unfortunate view emerging within the growing anti-science movement is that folks in public health are indifferent to individual freedoms, and that public health policies are too paternalistic and constraining. For infectious disease prevention, this has come up vividly with opposition to mandatory vaccination policies or mask requirements for COVID-19, while pushback on measures to curb non-communicable diseases have been seen in response to portion control restrictions and indoor smoking bans.

What I would want people to understand is that public health researchers are always concerned about the impact of their work: whether costs exceed benefits, and also whether certain people benefit more or bear the cost more than others. Often, public health interventions are meant to protect those who are especially vulnerable, as well as provide benefits to the public at large. Bans on indoor smoking in restaurants, for instance, protect patrons, but also look out for the restaurant staff. Waiters and bartenders may have no choice about their exposure to indoor smoke, so they disproportionately carry the burden for others’ choices. 

Is there anything you would tell people interested in becoming a public health scientist? 

You can do an incredible diversity of things as a public health scientist! You can learn about demographic dynamics to predict what populations will look like in 50 or 100 years. You can think about health economics to understand health behaviors and the distribution of health resources. You can study epidemiology to learn about the causes of disease burdens—and the factors you can intervene on to reduce that burden. And you can study ethics, to evaluate how to make trade-offs between maximizing population health and achieving other valuable goals, like improving equity, reducing poverty, and facilitating peoples’ freedom to define their lives.

The thing I would encourage people interested in public health to understand is that how we take care of public health is a reflection of how we care about our society. You need to be willing to think critically about what aspects of human welfare you are trying to help improve, what does improvement mean, and what values does that articulate and express. Beyond being a good researcher, I think public health requires that you be a good humanist, and that you care about the broader human experience. Put simply, we’re not alone—we live, together, in a society, one that involves certain rights and obligations. One of those core obligations is to look out for one another. 


To learn more about Daniel’s work: 

  • Follow him on Twitter: @Daniel_A_Arias
  • Check out this article about his recent work here.

This interview with Daniel Arias, PhD student in the Population Health Sciences program of the Harvard Graduate School of Arts and Sciences (associated with the Department of Global Health and Population at the Harvard T.H. Chan School of Public Health), was conducted and edited for space and clarity by Malinda J. McPherson in September 2020. 

Malinda J. McPherson is a PhD candidate in the Harvard University/MIT Program in Speech and Hearing Bioscience and Technology.

Cover image: “Crowd at Knebworth House – Rolling Stones 1976” by Sérgio Valle Duarte is licensed under CC by 3.0.

This piece is part of our special edition on the day-to-day lives of researchers working in many different fields of science. Are you interested in learning about a different type of scientist? Check out the rest of the special edition!

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