Accurate time estimation is a skill essential for good project management. It is important to get time estimates right for two main reasons:
- Time estimates drive the setting of deadlines for delivery and planning of projects, and hence will impact on other peoples assessment of your reliability and competence as a project manager.
- Time estimates often determine the pricing of contracts and hence the profitability of the contract/project in commercial terms.
Often people underestimate the amount of time needed to implement projects. This is true particularly when the project manager is not familiar with the task to be carried out. Unexpected events or unscheduled high priority work may not be taken into account. Project managers also often simply fail to allow for the full complexity or potential errors and stuff ups, involved with a project. The 2004-2006 Wembley Stadium project in London is often used as an example, although there are countless others of less profile.
Time estimates are important as inputs into other techniques used to organise and structure all projects. Using good time estimation techniques may reduce large projects to a series of smaller projects.