In talking with many organizations about their IT estimation practices over the years, I’ve noticed a recurring theme has been their self-perception of immaturity when addressing the use of a commercial estimating tool. Estimates in the workforce are typically generated via the Delphi method, multi-tabbed spreadsheets, and uncalibrated guesses. When recommending a top-down tool approach, the feedback can be: “we aren’t mature enough to use a tool or model.”
I’ve actually seen the opposite. The top-down approach offers an on-ramp to more formal estimating by its very nature of needing few inputs, rather than the myriad of cells, rows, and columns required to be populated in a spreadsheet. A top-down tool approach leads us away from relying on the institutional knowledge of a few people that may have relevant experience, but one day may retire or move on from the organization taking that knowledge -with them. Also, a parametric top-down approach leveraging relevant historical data is much better than a wet thumb in the air.
Maturity can have different “faces.” It can be formal and wide-ranging, as it was in the old CMM. In the mid-1980’s, the CMM (Capability Maturity Model) was introduced via a study funded by the USAF to understand why a recent round of projects overshot their schedules, budgets or ultimately abandoned. This was an attempt to instill compliance, validation, and guardrails for measuring software development maturity. The CMM (now CMMI) is still practiced, but to a lesser degree in the wake of other methods. Even so the idea was to foster a general consensus of what maturity looked like to the DoD.
Or it can be informal and centralized. A top-down tool approach fosters a repeatable and transferrable capability that can be achieved by one, a few, or many people supporting the development organization. Let the tool do the heavy lifting for you - the small number of inputs coupled with the calibration of historical data and tool algorithms drive down the need for being as mature as one might assume. Like with everything else in life, the more we do it, the better we become.
A top-down tool approach is inherently simpler than the aforementioned manual techniques, requiring less expertise by the estimator and less data to input. I’ve supported many clients that initially had a preconception that their organizational maturity was too low to use a top-down tool. Then, after generating realistic and defensible estimates, they realized they had the maturity all along. What they once thought of as maturity obstacles, such as learning curve, user expertise, and time needed to become self sufficient on the tool, all went away after adopting the top-down approach, largely due to its simplicity.
Of course, all of the above is relative to the nature of estimating. It can be a complex endeavor, but I’d submit that a top-down tool approach offers a less daunting introduction.