Save Your Butt With a Bridge Chart

If you’re explaining, you’re losing is an old adage in politics. To this, let me add the converse: if you’re losing, you better start explaining.

The chart of choice when things aren’t going right--or when people doubt they’re going to go as well as you say--is the bridge chart. Sure, it could be used in other scenarios, but I only associate it with gloom and doubt. Wikipedia says it’s more commonly called a waterfall chart and implies it originates with McKinsey. If you don’t know the name, maybe you’ll recognize it on sight. See the figure below.

This is a lot simpler type of chart than the mekko chart (see my previous article, https://bit.ly/2hppRCH). Whereas mekkos excel at comparisons, the bridge chart adds causality to the picture. Usually it’s used to graph temporal change: this is where we were, this is where we are, here’s how we got there.

The figure above illuminates how company Alpha experienced a revenue decline from Q1 to Q2. Pill and poison sales fell but potions grew, resulting in revenue falling 15 pesos in total to 120 pesos.

For other examples, see Ericsson’s 3Q16 earnings slides (https://bit.ly/2g8ZBeL). One-third of the deck is bridge charts. Slide 12 exemplifies annotating a chart to convey additional meaning, highlighting the advantage of a visualization with a lot of white space. Slide 15 layers on even more content and shows how additional colors can be put to work in a bridge chart. Each type of cash flow has its own color in the chart, with like-colored rectangles overlaid on the chart to total the changes by type. A chevron shows the grand total.

In another example, Point Topic uses bridge chart in an unusual way (https://bit.ly/2g90tjL), eliminating the start and end towers of the bridge, leaving only the deck. This example is also unusual in that it’s a rare example of this chart type being used to convey something other than bad news.

Nonetheless, a business insights and strategy director finding himself in the unenviable position of having to explain a sticky situation would do well to direct his team to draft a bridge chart. It’s a simple, effective, and familiar visualization.

Microsoft Office 2016 adds support for bridge (waterfall) charts. Like Excel’s other new chart types, the user interface is clunky and incomplete-feeling. For teams that don’t have the newest version of Office, it’s not hard to figure out how to use stacked column charts and clever colors to achieve the same effect. The excellent Peltier Tech charting add in (https://peltiertech.com/) is an althernative compatible with older versions of Office and offering multiple waterfall-chart options (sideways, stacked, etc) and more control over appearance.