Q&A

The problem with this depiction is the area each "death" is represented by on the page. A regular bar graph would give an equal spatial deption of each death, whereas this diagram creates a larger visual impression for those deaths on the outer perimeter of the pie chart. Nightingale maximizes her argument by putting the blue numbers on the outermost edge.

Unless, of course, she's assigned a set area to each death (e.g. 0.5cm^2), this is a great way to mislead people. Marketers make use of tricks like these all the time.

Yeah this data would be much clearer if she used a stacked bar chart. Her odd pie chart means that the area/radius issues make really understanding the plot very difficult. My management would never let me brief a general with a plot like that.

The blue area does not exactly represent deaths by preventable diseases. It is the area from the center to the edge of the blue. It is NOT a stacked chart, they regions are overlapping. You see this in November, when the black area is less than the red. She doesn't know how to represent this, so she simply makes the boundary line.

Overall, it was the first graph of its type, so for that it is interesting, but now that we know so much more, it isn't such a great example as some make it seem.

"She was the first to use the idea of a pie chart to represent data."

I question this.

Well, let's just say that she ventured out of her area of expertise on this one.