Something recently occurred to me. I’ve been researching chart and dashboard design standards for an article I’m working on, and the eventual inclusion in an upcoming book. Funnel charts are commonly used in the sales and customer relationship management (CRM) industry to visualize the volume of leads at various stages of the sales qualification process. Most of the leading reporting and chart tools include funnel charts – which are little more than a stacked colored band chart arranged in a funnel-shaped cut-out graphic. The metaphor makes some sense but I’m questioning the application. Every funnel chart I’ve ever seen is the same shape - a funnel with a linear taper down to a small diameter opening. The idea is that we start with a certain number of sales leads and then as they’re cold called, schmoozed and nagged by sales people, a certain number eventually will buy something. There are a certain number of stages in this process and at each stage, a number of prospects will fall away.
In some implementations of the funnel chart, the relative number of leads at a particular stage is represented by the height of the band within the funnel. I suppose this makes a certain amount of sense. One analogy would be that if you poured different volumes of liquids having different viscosities into a funnel, they would stack-up with different heights (remember JellO-1-2-3? – maybe not, I’m getting old).
Here’s my problem with the funnel chart: The funnel shape suggests that the volume of leads is somewhat proportional to the diameter of the funnel at some point on the vertical axis point representing a sales qualification stage. At the top, it’s wide and at the bottom it’s narrow to suggest that most of the leads don’t make it to the actual sales stage. Shouldn’t the diameter of each stage be consistent with the actual aggregate of leads for that stage? So if you were to sell stuff to every lead in the first stage and had no attrition at all, the sales funnel would actually be a cylinder. Is the industry using this funnel shape because the first person to design it was too lazy to do the math and draw a shape to represent the actual data? Sure, it would be a funny-looking funnel but it would look like that data rather than a linear funnel.
By the way, if you’re the guy who originally designed it and I get a comment that says “hey, butthead, I designed the funnel chart way back when and it seems to work just fine for a lot of people!” I’m not arguing that point. I just think it can be improved.
Weblog by Paul Turley and SQL Server BI Blog.