At its heart, building a business case is all about the numbers: No matter how good a “story” you tell about the project or initiative you’re proposing, if the math doesn’t add up, you’ll be dead in the water.
That having been said, all numbers aren’t created equal. A “hard business case” can be based on actual performance data, industry benchmarks, estimates built through sophisticated models, or even thumb-in-the-wind SWAGs—and more often than not, some combination of these (and more). But the kind of numbers you use in your business case have an impact on not only how it will be received, but also on how you’ll measure success, so you need to be clear about what kind of numbers you’re using (and how, and why).
A Number by Any Other Name
The best way to think about the kinds of numbers you can have in a business case is to place them on a continuum from most certain to least, as shown in Figure 1 and described as follows:
Figure 1: The Continuum of Business Case Numbers
In addition to the certainty of the numbers, the relevance, value, and authority are also higher the further to the left you move on this chart…as is the effort it takes to get the numbers.
The Final Word
As you can imagine, in just about any business case, unless you’ve done significant observation to set baseline process metrics, you’ll be forced to use more than simply observed numbers—and sometimes, you won’t have any observed numbers available at all. The challenge, however, is that each of these kinds of numbers requires a somewhat different set of assumptions in order to be useful, so weaving them together in a single business case (and then building a coherent and accurate “story”) gets tricky.
Overall, you always want to make sure your audience understands when you’re relying on which kind of number, so they can make their funding decisions with eyes wide open. And far from discrediting your business case because you don’t have “observed” numbers (i.e. the ones with the greatest relevance, value, and authority, requiring the greatest effort to compile), being transparent about where all your numbers came from lends credibility to your business case.
More often than not, your decision-makers have a gut feel that what you’re pitching makes sense and will be willing to seriously consider it, even based on industry benchmarks (i.e. with the lowest relevance, value, and authority, requiring the least effort). But what they won’t seriously consider is numbers that pretend to be something they’re not. That kind of incorrectly implied precision can kill your business case in a heartbeat—or worse, cause leadership to make bad funding decisions based on inaccurate or misleading information.