Wideband delphi is a process used to obtain an estimate by involving multiple estimators and combining their estimates. It has a complicated name but is a simple and intuitive process for producing better estimates.
Better estimates allow you to better choose and cost projects. A better estimate of the project can allow you to win more business with more competitive bids, and avoid unprofitable projects.
Wideband delphi should acheive a better estimate than individual estimation because it focuses on involving multiple experts, and combining their expertise in a way that achieves a better estimate than a simple mathematical combination of the estimate. In addition it also encourages break down of the item to be estimated into smaller items, another good method to improve the accuracy of the estimates.
Wideband delphi is a very simple process. You need an estimation coordinator and a number of estimators. Generally you do not want too many estimators as discussions will be longer and consensus will be more difficult to reach.
In the kickoff meeting describe the project to be estimated and its requirements to all estimators. Answer any questions raised to clarify the project as much as possible.
Each estimator breaks down the project into tasks, and estimates the tasks. These individual estimates must be written down.
Hold a meeting where estimators present their estimates and discuss reasons for the estimates. Because some estimators will see problems or solutions that others did not, the discussion ensures that during the next round of estimation each estimator will take more information into account in their estimates.
Repeat steps 2 and 3 as many times as necessary to obtain an estimate range with an acceptable level of variation between experts.
When you understand that the key to wideband delphi is the combination of multiple estimates by discussion, you can easily vary the process to suit your environment. Some simple variations might be:
With each estimator working on the same breakdown discussion can be focused on the estimates, rather than being split between estimates and breakdown. Estimators should still be able to add tasks to the breakdown to capture any additional work overlooked in the original breakdown.
By completing individual estimates and discussions in the same meeting time can be saved, particularly on small projects. It is still important however that each estimator estimates individually, writes their estimates down, and discussion only takes place after all have finished their individual estimation.
You could also have only a single round of estimation, with the discussion afterwards targeted to come to a single group consensus. The consensus can be in the form of a range which can limit the length of the meeting.
Wideband delphi is more robust than a single estimator coming up with a number. It has a number of similarities to agile planning poker, however it is different in that estimates for all tasks are completed up front individually rather than estimating and reaching consensus on each task one at a time.
You can use wideband delphi to improve the estimates for your next project. TaskTrakz project management software allows you to record your project task breakdown, along with one, two or three point range estimates for each task so you can easily record your wideband delphi estimates, and then execute the project directly on the same task breakdown. Get your free 14 day trial of TaskTrakz here.