Three additional chart/graphic types–
Readers love charts and graphs, as long as they’re easy to interpret. Unfortunately, as I stated in Part I of this article, some graphics give the appearance of transparent, valid data, but are deliberately misleading.
The Gantt chart
Gantt charts are an essential project management tool used to illustrate project timelines that help employees stay focused on key deliverables. They can be used to highlight a wide variety of variables, e.g., machine availability over time for different manufacturing teams, etc.
As with other chart types, Gantt charts can be used in combination with maps to show geocoded information, for things like the prevalence of HIV rates by metropolitan area or ranges of income by state. As with other graphics, use contrasting colors within the Gantt chart for easier interpretation.
The histogram (Bar chart)
Histograms are ideal for showing data distributed across groups of data. For example to display the relative heights of 200 professional basketball players, a histogram will display height from low to high along the horizontal axis and frequency along the vertical axis. You could do the same for numbers of students at different colleges/universities or frequency of recall rates for different vehicles.
In addition, you can superimpose a line of best fit (along the top of the bars) to give curvilinear dimension to your histogram.
The bubble chart
Bubbles aren’t so much a chart type as a tool to accentuate data on a background graph or map. People respond well to graphics with bubbles because they so elegantly display different magnitudes of a variable.
Using bubbles as an overlay on a map makes geographically related data easy to grasp.
In Part III of this series, I’ll provide background information on bullet charts, highlight tables, and treemaps.