Better BI

Describing the elements of bullet graphs is the first step towards being able to discuss and design them.

This diagram, copied from Steven Few’s Bullet Graph Design Specification shows the analytical elements of a standard bullet graph:

• the data – the performance measure, comparative measure, and the qualitative ranges;
• the quantitative scale provides the analytical framework for the data;
• the text label identifies the business context for the data.

This diagram segments the bullet graph into its structural parts.

• The graph body is the graph’s core containing the data.
• The quantitative scale provides the numerical framing for the body’s data.
• The text label identifies the business context.

This diagram segments the graph into its geometric and textual elements.
The geometric elements have fixed dimensions, orientations, and alignments, and are therefore easily constructed and positioned in the 2D graphical space.
The text elements are different in that their dimensions will vary depending upon their contents. Most notably, the characters, and font style and size will directly affect the 2D graphical space required to present the text. Different rendering systems will further affect the text display dimensions.

Considering the bullet graph with separate and distinct geometric and text elements simplifies the process of constructing graphs from real data.
Creating the geometric elements is straightforward, as their dimensions and coordinates are invariant across rendering systems.
Creating the text elements contents is similarly straightforward. Determining their dimensions and coordinates (D&Cs) is difficult due to the differences to rendering text by individual SVG user agents. This makes calculating the text elements’ D&Cs effectively a best-guess approach. In practice, this may be “good enough”, but mechanisms must be provided for specifying the actual D&Cs producing the optimal results for a given user agent—this will be covered in future posts.