Cantilever estimation uses two methods of forecasting to combat Hofstadter’s Law:
- Reference-Class forecasting: gathering historic examples of similar projects that Cantilever or individual team members at Cantilever have undertaken
- Work Breakdown Structure Estimation: Breaking down a project in granular detail, down to the core tasks anticipated
These techniques appear to be in conflict, but they dovetail in a few important ways for us, and we find that using them redundantly provides more accurate projections overall (probably due to a "wisdom of the crowds" effect).
Our core estimation method is the WBS. We break down every phase and deliverable into its constituent parts, then estimate each part individually rather than looking at large deliverables as a monolithic piece.
Secondly, reference-class forecasting provides us with an overall initial ballpark for where the project might end up. Assembling a class of similar historic projects will provide at least an order of magnitude for the new project that is fairly reliable if the sample size is anything more than tiny. If you are newer to the company and don’t have a rolodex of prior project results in mind, ask Ty. We are working on an update to the project database that will make this easier and more streamlined.
With WBS estimation, since our projects involve doing similar granular tasks on many projects, reference-class forecasting allows us to make more accurate estimates for each individual task. For instance, creating a sitemap is something we do on virtually every project. If we review how long it has taken on five similarly-structured projects, we are likely to have a good measurement for what it will take on a new project.
On any given new site build, we have probably done 80-90% of the constituent tasks before, just perhaps not in the same orientation or with the same parameters. Looking granularly provides more specific reference-class data to analyze.
Estimation is also a collaborative art. Use your teammates, especially those who have worked on similar projects, to provide second opinions on each granular projection. Use the client as well. In keeping with Cantilever’s core value of transparency, we frequently share estimates with clients or leads. In addition to bolstering trust between the parties, clients can also point out erroneous work or missing items in our WBS.
Please review the sales Drive to find estimates for similar prior projects. We are also making a series of sample estimates to help in creating a WBS. Here is the first:
Here is a video of Ty walking through this methodology: