Database Reference
In-Depth Information
The following sections examine these visualizations in more depth and also
describe how you can combine the different visualizations to better present
your data.
TIMELINES
Joseph Priestly's timeline of lifespan shown in Figure 11-1, is the earliest example
of this form of chart, and it shows many of the key features that we still use
today. Note the labeled timeline—running from 600 BC to 0 AD. The length
of the line between the birthdate and the date of death of each man shown
on the chart offers an easy way to see the lifespan of each.
F I g u R e 11 -1
An early timeline chart created by Joseph Priestly
A timeline has a graphic—a bar or a line—to show the start and end dates of
an event or series of events. Timelines are useful in instances where you do not
need to show a metric but rather a sequence of events, using the length of the
line to delineate the length of time that has passed and showing qualitative
metrics. Sometimes the qualitative metrics can include great detail, especially
in an interactive version of the timeline is available where detailed write-ups
of the event can be expanded.
Timelines are visually very similar to both bar charts and Gantt charts. Which
chart is used depends on the context. Timelines are used primarily where no
other data points are being shown, and qualitative data, such as the names of
people or battles, need to be highlighted. Bar charts are used where additional
data need to be shown, for instance using the color of the bar to distinguish
