Jocellyn's Blog

What is wrong with that graph? (Visu homework III.)

Not every visualization which is out there is a good one. There is an article trying to summarize criteria for judging good or bad visualization called “Junk charts trifecta checkup” and which can be found here. According to this framework, visualization should be judged based on 3 questions:

  1. What is the question?
  2. What does the data say?
  3. What does the visualization say?

Some visualizations could have nicely done visual part and good source of data which were well prepared but could fail in answering some interesting question (problem in Q). Others could ask the right question and use nice and proper chart but the data may fail to answer this question (problem with D). Lastly, the data and the question may be good but the visual representation could be comopletely off (problem with V). These problems (Q,D,V) could be combined and mixed up together.

As my third homework for my data visualization class I needed to find any visualization online and judge how well it is done (and suggest improvements). I am going to use the above summarized criteria and I am going to criticise this graph, taken from our local online newspaper site:

blesk

The chart is asking the question “Do you think that police and local authorities try to solve the neighbour issues and problems?” And the results are “Always with full responsibility”, “Only formally”, “Only in some cases (e.g. celebrities)”, “Absolutely not” and “I do not know”.

So what is wrong with this chart? Lets take a look at each of the question:

Data

The data is very missleading - the only negative possibility is very strong - “absolutelly not”. So no one in the questionaire answered simply “I do not think they try to solve it” ? I think the grouping of the answers to these categories are bad. Also it is unclear what is good and what is bad - if police solve the problem only in some cases, does it mean they do their duties only half time? What goes under “only formally” and again, is it good or is it bad?

Question

This chart was used in the article about violence in the neighbourhood - I can understand what the author wanted to illustrate. He may wanted to say that people doesn’t trust the police when it comes to local issues with violence. The question is however asked in unclear way: is it asking if the policy solve that at all or if it is solving it properly? In another words, is it a question about the extent and dilligence of the police or a question about their ignorance / non ignorance? The first answer is addressing both - it says yes and with full responsibility, however the other only say something about the nature. The policy could solve the issues only formally but solve all the issues alway or they could solve them only formally and even fail pay attention to it.

Visualization

The chart is just horrible. First and most important - the bar chart is not a good fit! These are relational data which adds up to 100% - they should visualize the ration between people’s opinions. Whats even worse is that 36.1% which looks like 100% because it goes to the full width of the chart!

Also the colors are used weirdly. I got that the author wanted to group positive answers with blue and negative with red, but why the missing answer (“I don’t know”) is green? And why are the first 3 options grouped together? Is it a good thing that the police solve it only formally? Isn’t it rather a half-half case?

Reccomendations

Please, author of this chart, take my advices and redo this chart:

  1. Use a pie chart. It is the best fit to display how people opinion is divided from 100%.
  2. Are you sure that the people answered only in these categories? maybe the questionaire was not so good, what about doing the research again?
  3. If you must group items based on colors, group the obviously positive with green, the half-half with blue, the negative with red and the absent value with gray.
  4. Do not try to make the chart pretty just by throwing some shadows on it. It looks rather weird that all the bars have shadows except the green one.
  5. Think about the the question - are you asking if police is dealing with it or if it is doing it properly? These are very different questions and you seemed to mixed it up together.

Overall, it is a very ugly chart which is not saying much about the topic. But this was a good exercise to realize what coud be wrong - for the first sight I just did not like the visuals and did not have a clear idea why. After a little bit of thinking I came up with a few very concrete reasons why I do not like it and I think it is very unclear.



Comments

comments powered by Disqus