I was hungry, saw this graph and it caught my attention, but made me even hungrier :(. The graph supposed to show the distribution or perhaps popularity of pizza topping among UK people. One nice thing about this visualization it is grabbing attention very well; the picture looks very sharp and vivid. However that’s about only good thing about it. Upon closer inspection I started noticing things that are not right about it.
- It appears to be a bar graph made to look like pizza, the idea is cool but, using different pizza toppings as slices creates optical distortion so user will not be able to tell the different percentage accurately. It might seem as a good idea to show a picture of category rather then put a simple label. However they still needed to write labels in order to represent their data. Also it is possible that slices become small enough so it is hard to tell what kind of pizza toping it represents. Is it piece of bacon or ham?
- Categories do not add up to a 100% or to some defined total number of something. You never use pie chart if the pieces do not add up to a 100% or a total amount of something whole. In this graph they do not. What is even more confusing is that some categories have 2 sets of percentages. How do you interpret that? Is it percentage of a whole or just split to subcategories within category?
- Also on the bottom of the page there are even more categories that were not included in the diagram at all. What is the purpose to do visualization if not all data is included, especially trying to represent it as pie chart.
- Does the graph add any clarification to the information? No, it is actually making it confusing. The data presented probably needs to be visualized via series of bar graphs. Putting data in pie chart format just conditions the brain to think in a way that makes it hard to understand the data.
- The biggest revelation her is probably the graph was there just as picture not a bar graph at all. However such beatification is not acceptable! Faking the graph drastically changes people’s perception of presented information.
- Graph also presents false data correlations; For example, ham and pineapple are put together on one slice, however they are reported separately by different percentages. So in theory people who voted pineapple might not have selected ham, but the image implies that it is a bacon pineapple combo pizza to reader of the graph. Even better example is olives; they are present in 2 different kinds of pizza but reported only in one.
To summarize this review I think it is fair to say this graph creates more problems than it solves, just reporting categories using simple text line by line would create much less confusion for the reader . But would it have captured my attention? Is a whole different question to consider.