Epidemiology vs. Biostatistics: Understanding Their Roles in Public Health

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Two doctors examine an image of a human body.

Where do illnesses come from? Why do some people get sick, while others remain well? Which diseases are most prevalent in a given city, state or community, or among a particular population group?

Each of these questions is critical in the public health field, in which professionals seek to promote entire populations’ overall physical health and well-being. To help answer these questions, and ultimately to advance better health outcomes, public health experts rely on the scientific disciplines of epidemiology and biostatistics.

These disciplines, while overlapping in several ways, are distinct from each other. This article will consider the similarities and differences in epidemiology vs. biostatistics, as well as the roles that both disciplines play in promoting public health.

What Is Epidemiology?

Epidemiology is a health care discipline with an important distinction: The “patient” isn’t an individual, but rather an entire community or population. Specifically, epidemiology uses science, systems-thinking, and data to determine the underlying causes of different diseases and health outcomes in a population.

Epidemiologists tend to focus on two areas: distribution and determination.

  • Distribution refers to the frequency of a particular disease or health outcome and to any patterns or trends that may be identified
  • Determination is more concerned with cause and effect: What are the risk factors associated with a disease? What are its underlying causes?

Epidemiologists focus narrowly on a particular population — whether it be a nation, a state, a city or even a small neighborhood. Additionally, epidemiologists study any and all events that pertain to population health. In other words, epidemiologists study not just diseases but also any external factors that cause people to become sick, injured or impaired.

The Scope of Epidemiology

Epidemiologists’ work encompasses a wide range of issues. The Centers for Disease Control and Prevention (CDC) lists six categories in epidemiology.

Environmental Issues

Epidemiologists may study any environmental exposures that contribute to population sickness or wellness. For example, what’s the local air quality? Are there potent allergens or asthma triggers? Does the local water supply contain any harmful substances?

Infectious Diseases

Epidemiology concerns itself with infectious diseases, as well, which may include anything from foodborne illness to seasonal flu. Historically, epidemiology has played a vital role in developing a clear understanding of pandemics such as typhoid and cholera.

Noninfectious Diseases

Noninfectious diseases can include a local risk for a particular type of cancer or a high rate of diabetes in a particular community. Epidemiologists may study the potential factors that contribute to these conditions.


Epidemiology also includes the study of injuries, such as local rates of gun violence or homicide. Researchers consider factors that make these injuries more likely and also explore their impact on the community’s physical and emotional well-being.

Natural Disasters

A natural disaster’s short- and long-term effects may warrant epidemiological study. Natural disasters can be anything from hurricanes to wildfires to earthquakes.

Acts of Terror

A final category for epidemiological study is terrorism. According to the CDC, professionals in the epidemiology field may study the effects of incidents like the World Trade Center attacks or biochemical weapons deployment.

There are five major areas of study for epidemiologists.


What Do Epidemiologists Study?

The process that epidemiologists employ involves several core metrics –– each one is used to evaluate different health outcomes and to develop strategies to promote public health.

Epidemiology Metrics

Epidemiologists monitor four essential metrics to understand population health outcomes: disease dispersal, disease factors, disease populations and health-related impact.

Disease Dispersal

Epidemiologists are concerned with how common or rare a disease may be as well as any potential patterns to its development. For example, does the disease occur more frequently in men or women? Does it occur in certain age groups? Does it occur during certain seasons?

Disease Factors

Epidemiologists also look at some of the underlying factors that make an individual or a population more prone to adverse health outcomes.

Disease Populations

Which populations does the disease seem to most acutely affect? Has the disease spread beyond a particular neighborhood, city or state, or is it more contained?

Health-Related Impact

Epidemiologists study a disease’s or a health event’s overall impact on a population’s physical and mental well-being. Epidemiologists may also consider any related social or economic disruptions.

Learn More About the Study of Epidemiology

For further exploration of what epidemiologists study, consider the following resources:

What Is the Role of Epidemiology in Public Health?

History provides many examples of how epidemiologists have played a role in promoting health, curbing the spread of disease and developing strategies to address widespread illnesses.

Foodborne and Waterborne Diseases

Epidemiologists have performed highly consequential work connecting rampant diseases with environmental causes, such as pollutants in local food supplies and water sources.

Thanks to epidemiologists, we know that typhoid is widely associated with poor sanitation and dirty water. This information is useful not only in identifying high-risk areas but also in preventing a typhoid outbreak.

Epidemiologists also discovered that cholera comes from contaminants found in feces, which can sometimes be spread to food and water sources due to overall lack of sanitation and hygiene.

Viral Infections

Epidemiologists have done important work tracing infectious diseases. Consider three examples:

  • As the CDC points out, researchers played a major role in exploring the 1918 influenza’s genetic makeup. Epidemiologists used that information to better prepare for future disease outbreaks.
  • Epidemiology has also provided an overview of the global HIV crisis, helping researchers identify trends, patterns, “hot spots” and means for disease control. The World Health Organization (WHO) provides a detailed summary of this work.
  • More recently, epidemiologists have been hard at work tracing COVID-19’s cause and seeking the best ways to control its spread. The CDC provides an ongoing account of this work.

Famous Epidemiologists

Many famous epidemiologists have contributed to the field of public health. A few noteworthy examples include the following:

  • John Snow was a British physician whose cholera studies proved foundational for modern-day epidemiology.
  • The American virologist Nathan Wolfe performed innovative studies on the nature of infectious disease spread.
  • Thomas Francis Jr., an American microbiologist, helped isolate different influenza strains, enabling more targeted treatment.
  • Another American researcher, Paul Farmer, is noted not only for his work in epidemiology but also for his advocacy for robust health care in underserved populations.

Additional Epidemiology Resources

To find out more about epidemiology’s role in public health, check out these resources:

What Is Biostatistics?

Biostatistics is often considered in conjunction with epidemiology; though related, these disciplines aren’t the same. Biostatistics, which is also called biometry, studies biological phenomena through the use of statistical modeling, methodologies and processes. The biostatistician may design a biological experiment, and then collect and interpret the data that the experiment yields.

Biostatistics provides the foundation of much epidemiological research. In other words, epidemiologists often use biostatistical principles and methods to draw data-backed, mathematical conclusions about population health issues.

What Do Biostatisticians Study?

Biostaticians may study diseases, disorders, and health risks associated with certain behaviors or health risks associated with the local environment.

Biostatistics Methods and Procedures

Biostatistics is considered one of the foundational disciplines in public health. Specifically, biostatisticians conduct quantitative and qualitative research to help identify population health trends and risk factors. This work may involve several methodologies, including the following:

  • Clinical trials
  • Focus groups
  • Surveys
  • Case studies
  • Field observation
  • Laboratory experiments

Through these and other methodologies, biostatisticians gather and analyze data, which may lead them to statistically significant conclusions about how different diseases originate or spread. These findings often provide clues as to how these diseases may be controlled, prevented or eradicated.

Biostatistics in Action

For examples of what biostatistics may look like in practice, consider the following:

  • Some statistical researchers may focus on a particular population, such as infants or older adults, and study conditions that seem especially popular among the demographic in question.
  • Others in the biostatistics field may look at a specific health concern, like obesity or diabetes, using statistical trends to identify possible causes or risk factors.
  • Biostatistics can also encompass the study of environmental factors or the effects of a particular therapy or clinical intervention on patient outcomes.

How Findings Are Presented

The results of biostatistical studies may be shared with other researchers in the epidemiology field or even be made available to the general public. Typically, this information is presented in one of the following ways:

  • Research papers
  • Journal articles
  • Conference presentations
  • Published books

What Is the Role of Biostatistics in Public Health?

Biostatistics has been used throughout history to improve public health outcomes. Here we consider several case studies.

Cancer Research

Biostatisticians have played a long-standing role in oncology, designing experiments to better understand how and why cancers form and how they may be effectively treated. Biostatistical research in oncology includes a wide range of clinical trials, focusing on patient populations of different sizes and at different stages of treatment. Through these trials, researchers have developed a greater understanding of genetic markers that make a person more or less at risk for different kinds of cancer.

Environmental Factors in Public Health

Additionally, public health professionals who work in biostatistics have conducted important investigations on how air pollution, water contamination and other environmental factors may impact a local population’s well-being. Through surveys, clinical trials and field observation, biostatisticians have made important discoveries about how toxic substances and hazardous waste may impact different populations, identify links between local infrastructure and population health, and even determine the effects of climate change on different communities.

Statistical Genetics

A significant subdiscipline of biostatistics is statistical genetics. Researchers in statistical genetics use different statistical methods to draw conclusions based on genetic data. Statistical genetics provides insight into how different genes:

  • Affect particular diseases or health conditions
  • Impact a “normal” phenotype
  • Have evolved and adapted, specifically within particular demographics

The inferences can help clinicians identify patients who may be at a higher risk for certain conditions, making preventive treatment a possibility.

Human Growth and Development

Biostatistical research has also provided benchmarks and reference points for normal human growth and development. By surveying growth trends across broad sample sizes, researchers have developed a better understanding of how children and adolescents grow, which factors support healthy growth and which factors may stunt it.

Additional Resources

To find out more about biostatistics, especially regarding population health, take a look at these resources:

Epidemiologists and biostatisticians have different approaches to keeping the public healthy.

What Is the Difference Between Epidemiology and Biostatistics?

Biostatistics and epidemiology are often seen as closely related. The reason is that both fields consider population health concerns, and both fields have the ultimate goal of promoting overall health and disease prevention in a specific community.

Biostatistics may be understood as one of the tools that epidemiology employs; that is, an epidemiologist may use biostatistics principles to help process data and to make helpful inferences.

Despite their overlaps, epidemiology and biostatistics differ in several important ways:

  • Epidemiologists typically focus on pathogens and epidemics; they are concerned with specific health-related events. Biostaticians, however, focus on broader biological issues, such as those related to genetics.
  • Epidemiologists will usually specialize in the cause of diseases and the different factors that contribute to population health problems. Meanwhile, biostatisticians typically specialize in the effects of health issues, for example, the implications of genetics, the environment or biological factors.
  • Epidemiologists can be involved in community outreach programs, which require strong teaching skills. This type of public education effort isn’t usually part of the biostatistician’s job description.
  • Biostatistician roles, even more so than those of epidemiologist roles, typically require strong computer skills and project management competencies.

Promoting Public Health Through Scientific Study

To keep communities safe and healthy, public officials need to have a clear understanding of different factors that impact the health of individuals and the population as a whole. Through scientific inquiry, both epidemiology and biostatistics provide this understanding and lay a foundation for greater health and well-being throughout our communities.


Infographic Sources:

Centers for Disease Control and Prevention, What Is Epidemiology?

PayScale, Average Biostatistician Salary

U.S. Bureau of Labor Statistics, Epidemiologists

U.S. Bureau of Labor Statistics, Mathematics and Statisticians