Choosing a visualisation type requires decision along two axes:
- what is the type of data you visualise
- what is the expected level of attention from your audience
1. Type of data
- A single variable/number, a key message or indicator: BAN / sparklines
- Two or more variables: chart - comparison, composition, relationship, distribution
- Two or more variables with a geospatial element: map
2. Level of attention
A helpful heuristic: 3/30/3 rule. When you create a visual you can expect either: 3 seconds, 30 seconds, or 30 minutes of attention from the reader (this might vary in reality, of course. But it will be a lot shorter than you think - or hope). With this guideline in mind you can determine the appropriate level of detail for your visualisation.
- 3 seconds: Deliver a single, immediate insight with minimal cognitive effort.
- 30: seconds: Communicate one main message requiring light interpretation.
- 3 minutes: Enable deep understanding, exploration of nuance, and multi-layer context.
3/30/300 rule. To determine the appropriate amount of detail for your visualisation. You can divide your visualisation according to the 3/30/300 rule. The person reading your chart will spend either 3 seconds, 30 seconds, or 300 seconds (=5 minutes) looking at your visualisation. Or maybe just 3 seconds, 30 seconds, 3 minutes
- 3 seconds: Infographic: management/executive audience. Fast & easy decision or insights, actionable information, 2 colours. BANs, locator map with relevant locations or 1 or 2 annotated incident highlights. Sparklines
- 30 seconds Narrative visual: public/general audience, engage or generate interest, up to 6 colours, strong visual hierarchy, graphical grammar
- 300 seconds: Data exploration visual: staff/expert audience, big data visualisations, sharing knowledge, present multiple or complex ideas, minutes of engagement, custom mapping conventions
What are you visualising? A single variable/number, a key message or indicator: BAN Two or more variables: chart - comparison, composition, relationship, distribution Two or more variables with a geospatial element: map
A successful design begins with knowing why the map is being made. Cartographers begin planning maps by asking themselves and their clients several questions:
- What information is being mapped?
- Who will be reading the map?
- Is the map content coordinated with written text or other graphics?
- What size and medium will be used to display the map?
- What are the time and budget constraints on map production? If the audience is new to the information mapped, they may require a simpler presentation. Likewise, if they are too busy to spend much time reading, they will also need a simple map that summarizes the information. Maps for nonexperts or busy people […] should have a single message that focuses the attention of the reader. Well-designed basemaps are built from the ground up, from landform to land use to line and point overlays: