List: 2 Life Changing (Saving) Visualisations on Healthcare

The 2 vizzes that I am about to discuss in this post are 2 of the most influential vizzes ever. Both are vizzes about healthcare. They are important not only within the space of data visualisation, but they are also critical to saving lives when they are used. The 2 vizzes are:

1. John Snow's Cholera Map
2. Florence Nightingale's Rose Diagram

These 2 vizzes coincidentally are published in the 1850s and are about healthcare issues. These shows are forward-thinking they have been in applying data visualisation to their work successfully. Perhaps, it may be a pity that we are still having to promote data literacy and data visualisation in the 2020s. Not all offices or management teams are keen on tapping on the power of data visualisation for decision-making despite the lessons from history. 

Below are my thoughts in the form of ABC and DEF for the 2 vizzes respectively.

1. John Snow's Cholera Map

a. Actionable Analysis

It is said that Dr John Snow used his map on the cholera cases to stop the outbreak in Soho, London 1854. Although there are some suggestions that John Snow's map is not the end all be all that ultimately stopped the cholera outbreak in Soho, he certainly contributed to the discovery over several years of research, and his map became a useful way to illustrate the Soho data.

b. Basic Blocks

Marked using little blocks, the concentration of cholera cases can be seen clearly. Using this map, Snow and other scientists were able to trace the cholera outbreak to a single infected water pump. A clever combination of a unit chart on a map, the map actually gives a better way to count cases as compared to the usual use of circles that are different-sized circles or colour-coded areas on maps even the modern times using our digital tools. The numbers are noted on the map clearly unlike trying to measure and compare values using areas or colours that have proved to be difficult.

c. Critical Cartography 

To confirm that the Broad Street pump was the source of the epidemic, Snow gathered information on where persons with cholera had obtained their water. Consumption of water from the Broad Street pump was the one common factor among cholera patients. After Snow presented his findings to municipal officials, the handle of the pump was removed and the outbreak ended.

Such is the use of maps and visualisation practically tapping into the power of both data and geography.

2. Florence Nightingale's Rose Diagram

a. Diagram for Decision

In 1858 nurse, statistician, and reformer Florence Nightingale published a chart that showed that epidemic disease, which was responsible for more British deaths in the course of the Crimean War than battlefield wounds, could be controlled by a variety of factors including nutrition, ventilation, and shelter. The graphic, which Nightingale used as a way to explain complex statistics simply, clearly, and persuasively, has become known as Nightingale's "Rose Diagram."  This demonstrated that charts that are not traditional (bar, line, or pie charts) can be useful too when it comes to real cases.

b. Effective to the Eyes

The chart is presented to the Queen and policymakers then, and the visualisation proved to be persuasive enough for them to take action based on Nightingale's report with the chart. As such, when it comes to chart design, a little flair and flourish may just make a difference.

The queen and Parliament could see at a glance the importance of hygiene; they quickly set up a sanitary commission to improve conditions, and death rates fell. Nightingale became one of the first people to successfully use data visualization for persuasion—to influence public policy.

c. Forward-thinking

With the right stats and the right design, the rose diagram has proved to be ahead of its time before the rise of digital tools to create charts easily. It takes effort, time, and an innovative mind to do it. 

Other “bat’s wing” diagrams were precursors to the rose charts. In one example, Nightingale compares the causes of English soldiers’ deaths during the Crimean War from April 1854 to March 1855 by month with deaths from April 1855 to March 1856. These diagrams were meant to show that sanitation efforts implemented in army camps and hospitals during the war dramatically cut soldiers’ deaths. The length of each radial line is proportional to the death rate for that month, with a large spike in deaths in January 1855.

But the text accompanying the diagrams suggested the shaded areas, not the radial lines, correspond to the death rate. Nightingale put an erratum on the figure and stopped using it, showing she arrived at her iconic rose chart through trial and, even, error.

All in all, it has been interesting and inspiring to read up on data visualisation and its history of it. Understandably, I am not the first to write about these, but I definitely am not the last. However, that is not the point of this post, as I hope readers are now keener to find out more.