Tom Steinberg of MySociety writes simply about visualisation:

“There are only two kinds of data visualization in the modern world. They are Story Visualizations and Answer Visualizations.

“Story Visualizations are those produced by one set of people with the goal of telling a story to an audience. Think of a newspaper graph showing deaths during a war, or a map showing where within the country unemployment is highest.

“The second kind of visualisations are Answer Visualisations. Answer Visualizations are produced to supply an answer to a single question posed by a particular person.”

Worth bearing in mind when you begin to visualise your data: are you doing it to tell a story, or to answer a question of your own?