When we think about pioneers in science and medicine, the usual suspects are often 鈥渇athers of鈥� something: the father of microbiology, the father of modern surgery, and so on. But Florence Nightingale, a 19th-century nurse, statistician, and public health advocate, was a pioneer in her own right 鈥� earning her place as the mother of data visualization and public health statistics.
Best known for her tireless work during the Crimean War, Nightingale revolutionized healthcare practices and significantly reduced mortality rates in military hospitals. But her legacy wasn鈥檛 just in nursing, it was her ability to communicate the urgency of sanitary reforms through the power of visual data.
The Crimean War: A Battlefield for Better Sanitation
During the Crimean War (1853鈥�1856), Nightingale and her team of nurses witnessed appalling conditions in British field hospitals. Soldiers were dying not from battlefield injuries but from preventable diseases like cholera, dysentery, and typhus. At one point, the mortality rate in some hospitals
Nightingale understood that improving sanitation鈥攙entilation, clean water, and better waste management鈥攃ould drastically reduce these deaths. But convincing politicians and military officials to invest in sanitary reforms required more than anecdotal evidence. It required data.
Enter the coxcomb diagram, or as it鈥檚 more commonly known today, the Rose Diagram. Designed in 1858, this circular chart visually represented monthly mortality rates in military hospitals, differentiating between deaths caused by preventable diseases (blue), battle wounds (orange), and other causes (black).
Image source:
As social historian and political economist , what made Nightingale鈥檚 Rose Diagram revolutionary wasn鈥檛 just its aesthetic appeal 鈥� it was its ability to tell a story:
- Before-and-After Comparison: Nightingale didn鈥檛 simply plot the data linearly. Instead, she created two distinct 鈥渞oses鈥濃�攐ne for the year before sanitary reforms were implemented (right) and another for the year after (left). This separation, using the same scale, made the dramatic decline in mortality rates impossible to ignore.
- Seasonal Patterns: The circular design highlighted seasonal variations in mortality, with larger wedges representing months where deaths were higher. This made it clear that preventable diseases spiked during certain times of the year, emphasizing the need for ongoing improvements in sanitation.
- Scaling for Clarity: Nightingale scaled her data by using a square root transformation, meaning the area of each wedge represented mortality rates. This is in contrast to a typical method of representing data by the height of a bar or location on a scatterplot, which tends to emphasize larger differences in values. Using square root transformation de-emphasized extreme outliers, such as one month鈥檚 exceptionally high death toll, and instead drew attention to overarching trends.
Notes on Nightingale
Nightingale鈥檚 Rose Diagram wasn鈥檛 just about science鈥攊t was a political tool. By presenting data in a visually compelling way, she cut through bureaucratic resistance and made an undeniable case for reforms. Her work helped persuade the British government to overhaul military hospital sanitation, contributing to a dramatic decline in deaths from preventable diseases.
Today, Nightingale鈥檚 Rose Diagram serves as a reminder that data isn鈥檛 just for analysis鈥攊t鈥檚 a tool for action. Whether you鈥檙e presenting to policymakers, advocating for public health reforms, or just trying to make sense of complex information, her example reminds us that how you present data can be as important as the data itself. It鈥檚 also a reminder to view data visualizations with a critical eye. If the creator of a data visualization has a personal or political objective, they can easily manipulate the data in ways that are not immediately obvious. There are dozens of approaches to , such as a truncated (incomplete) axis, inverted (reversed) axis, or a misleading colour scheme. Nightingale鈥檚 Rose was impactful precisely because it translated complex data into a compelling visual narrative, creating understanding among non-scientific audiences. With modern access to design tools and graphics today, readers should be aware that the striking nature of data visualization design can be used for both harm and good.
The next time you see an infographic or a dashboard, remember that sometimes a picture isn鈥檛 just worth a thousand words鈥攊t鈥檚 worth a thousand lives.
Note: This article was inspired by the authors鈥� coursework in PPHS602 at 不良研究所, the and .
