Redefining the Gantt Chart

Wikipedia defines a Gantt Chart as:

“A Gantt chart is a type of bar chart that illustrates a project schedule. Gantt charts illustrate the start and finish dates of the terminal elements and summary elements of a project. Terminal elements and summary elements comprise the work breakdown structure of the project. Some Gantt charts also show the dependency (i.e., precedence network) relationships between activities. Gantt charts can be used to show current schedule status using percent-complete shadings and a vertical “TODAY” line as shown here.”

And provides the following illustration:

Whilst I realise  the original purpose intended by its creator (Henry Gantt) was to present project management type information, he has actually achieved a whole lot more – hence I would like to re-define the Gantt bar.

If you break down a Gantt chart into its components, the bar has a start point, and a length which is plotted against a continuous date axis.  Multiple bars are then typically plotted by the introduction of a dimension on the vertical axis of the chart – these are usually tasks.

So what happens if we redefine the Gantt bar as:

“A bar plotted against a continuous axis.  The bar should have a minimum value specified, and typically a length.  The bar may be repeated by plotting against a discrete axis.

What happens, is you get a remarkably flexible chart type.  If you’re good with Tableau, you’ll be familiar with the Gantt bar– if not, take a look at some of the examples which ship with the product, and those which appear as visual examples on the Tableau website.

Here are some of the possible uses of our newly defined Gantt chart:

A stock price ‘candlestick’ chart

Shading areas between two lines using a Gantt bar

A tornado chart (questionable choice of chart of course)

Hopefully you’ll see that good ole’ Henry created something far more versatile than he intended – personally I think Gantt charts have little place in project management these days (I’m an agile kinda guy), so hopefully this post can go someway to repurpose them!

Tom Brown

London, UK