To be honest, I often found myself questioning the reality of the estimates when I started my career in project management. There was no consistent process for estimating project effort and what often happened was the work package lead would estimate the work to complete a deliverable, or a milestone, and base it on their experience doing the work. This estimating process only works if the person who creates the estimate is actually doing the work
In order to have a reasonable estimate of the project, the project manager needs to have a Work Breakdown Structure of the activities needed to deliver the scope of the project and real estimates of the time each of those tasks. The work breakdown structure is a graphic depiction of the scope of the project and is created by the project manager and the planning team. To create a schedule the project manager will take the list of activities and work with the project team to sequence the activities, assign work package leaders and determine the effort and duration of the the project.
When the project schedule is final, the project begins. If the estimates are reasonable, the project schedule can be tightened to shorten the duration if needed. Or, tasks can be re-sequenced to take advantage of resources. If the project estimates are optimistic, the project will constantly be in crisis as deadlines are missed. If the project estimates are conservative, then the project will take longer than needed, delaying the business benefits.
Following these steps will result in a reasonable estimate of the project schedule.
Using the work packages from the work breakdown structure to identify the project team
The work package leaders will meet with their teams to gather a three point estimate of the work effort for the activities, conservative, optimistic and realistic
Model the optimistic and conservative estimates
Input the realistic estimates into the project schedule
Validate the resulting schedule with the work package leaders and key stakeholders
It seems simple. Five easy steps and you have a reasonable schedule. In reality it is not that easy. People have other priorities than your project. Time to plan is not considered a high priority. and project managers are suppose to get things done, not spend time worrying about schedules. How do you overcome the challenges so that you have a successful project?
If you don’t have time to plan at the beginning, you’ll be spending more time managing issues through the project; it’s a fact of project management.
For step one, you need to ensure you have a planning team. These people may not be the ones on your project team but will have experience in the work you need to do. They will help you identify who you need on your project.
The purpose of getting a three point estimate is to help people come to a common time estimate. The optimists on the team will deliver a project schedule with no slack and no flexibility, the pessimists will give you a schedule that will delay the project benefits. If you need to speed up your estimating process and you have access to past projects, get one estimate and validate it against past performance. If you don’t have access to past projects, take the one estimate and during the validation process, challenge the team to question the estimates.