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Fall 2021
Willl Burtin (1908–1972) is famous for designing a graphic chart that showed efficiently how successful were three antibiotics on 16 different of bacteria. This chart was published in1951 and received many awards.
Burtin's Chart
A couple of different charts are used to make Burtin’s graphic: A radial column chart is layered on top of a doughnut chart. The radial column chart, untypically has the minimum value on the outer circle, and the maximum value on the inner center circle, that is because the columns are used to visualize the effectiveness of the different antibiotics; taller bars mean less quantities needed and show higher effectiveness.
The doughnut chart background is sectioned equally for each type of bacteria (with one section left for the scale of the radial column chart).
The legend on the bottom of Burtin’s graph allows the viewer to see two groups of bacteria. By reading length of the arcs the viewer can also determine which type of bacteria was more common in his experiments.
Finally, the clear center space is used to place a legend for the radial column chart layered on top of the doughnut chart.
Burtin uses a logarithmic scale for the radial column chart. “The scale varies from 1,000 micrograms per milliliter on the innermost ring to .001 micrograms per milliliter on the outermost” (Burtin). This scale allows him to map a larger range of quantities, multiplied by 0.1 as we move a step towards the outer circles, or multiplied by 10 as we move a step towards the inner circle. With this scale Burtin can map the largest value up to 1000000 times the smallest mapped value in a small space with a simple concentric grid.
The circular axes offer the advantage to present each category of antibiotic used on each bacterium, with no need for specific order in the way the categories are read, as we go around the chart, starting and finishing with the same category. this layout also offers attractive aesthetic appeal.
An Alternative Layout:
A non-circular way of mapping this data like a multiset bar chart or a stacked bar chart, would allow the viewer to compare the grouped variables to other grouped variables easily (quantities of the same antibiotics used on different bacteria). Since it is only three bars per group, it should be still easy to read and compare the quantities. To compare the sum of the type of bacteria on which the antibiotics are tested, the background can be split into two sides, one for the gram positive and one for the gram-negative bacteria, and on top of that the multi-set bar chart.
This alternative chart model using vertical and horizontal axes can be related in some parts to the “clarity, insightfulness and succinctness” that Chance’s editorial board attributed to Burtin’s chart, but not “originality and aesthetic appeal”. With a traditional scale, it will only be efficient if read looking for the least effective antibiotics. The last two qualities the non-circular chart might require more innovation. The unconventional scale used by Burtin makes the chart very useful. On another note, since there are three antibiotics, it would be interesting to create a 3-dimensional chart and exploring the possibility of mapping the bacteria in terms of depth as well.
The most effective part of Burtin’s visualization is perhaps the scale used for mapping the columns: through the circular layout and the “inverse” logarithmic scale (with the largest bars for the lowest quantities) Burtin’s chart allows the viewer to perceive which antibiotics out of the three tested are more effective (with less quantities needed), for each bacterium! In this case, the chart works as intended and allows the viewer to directly have their attention fall on the most stretched out columns to perceive effective antibiotics.
“The length of the colored bar is proportional to its effectiveness”- Burtin.
Source:
https://www.americanscientist.org/article/thats-funny
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