In A Description Of A Chart Of Biography Joseph Priestley offers an insight into some of the design decisions he took when working on his Chart of Biography, one of the earliest known timeline visualisations containing two thousand names and lifespans.
What has caught my attention when reading Priestley’s Description Of A Chart Of Biography, is how well one can relate to his process and the decisions he took when working on the chart, although he was designing for an entirely different audience and medium than we do today. It seems that the process for designing information visualisations has not changed significantly in more than 200 years.
I have extracted from his descriptions four general rules, that Priestley seemed to adhere to (consciously or not) and that I and probably many others still apply today:
- Establish Guidelines
- Before one can begin to put data into visuals, it is important to define some guidelines on how this transformation will occur. For it is always a transformation and only when it is performed in the same way for every instance of data, it is possible to contextualise and compare.
- Allow Interpretation
- There will be cases where a transformation can not be performed in the way intended. At first, one should check whether this might be due to a mistake in the guidelines and, if yes, adapt the guidelines for all elements. However, often this can lead to things feel right in one case, and feel awkward in all the others, at which point it is important to trust one’s instinct as a designer and break one’s own rules.
- Allow Redundancy
- Tufte’s Data-Ink Ratio is an encouragement to remove clutter from data visualisation, however one should not refrain from displaying redundant information when it helps the usability and understandability of a graphic.
- Allow Involvement
- A visualisation should not be designed to simply be looked at, but to be used. During the design process one should keep in mind how a user might potentially interact and interfere with the graphic, be it a printed, digital or physical implementation.
After the jump, I will show by example how those rules have been applied by Priestley.