These two Gantt charts, are for the same project with the same start date, deliverables, task durations and team members. The one on the left is a traditional Waterfall project with the full design up front, it ends in June. On the right the project is setup using a Scrum framework, it includes Scrum events (highlighted in yellow), but it ends one month earlier, on May 1.
With the Waterfall methodology, the process is designed so the next phase is not started until the current phase ends. With Scrum, once a few deliverables are defined enough for development to start, the development team starts building those items. In the meantime, the other requirements are refined and User Acceptance Testing occurs on deliverables already built.
Each iteration, the development team builds potentially releasable results. This way the end user doesn’t have to wait until the end of the project to start using the deliverables, they may be able to start using the deliverables that meet the “definition of done”.
If priorities change, and half way through the project it needs to be put on hold or cancelled, generally the end user doesn’t get to use any of the deliverables. With an iterative, incrementally developed project, like what is used in the Scrum framework, some pieces may have already been delivered. In this case two items have been delivered (highlighted in green) by March 31 and another completed User Acceptance Testing, so it too may end of being implemented prior to stopping the project.
With traditional Waterfall projects, if a requirement changes, a change request process is invoked, which generally adds time on to the project. With Scrum, a change is just added to the Projected Backlog and handled like any other requirement.
Usually traditional Waterfall projects, only deliver the product at the end of the project. The rules of Scrum dictate that the most valuable items are worked on first, and incrementally add on to the product. Which creates the possibility that towards the end of the project, the team, along with the customer, may determine the lower priority items really don’t have enough value to continue development. So they are eliminated and the project ends.
For some projects it makes sense to use the traditional Waterfall methodology. But many other projects can benefit from the Agile properties of iterative incremental development that are incorporated into the Scrum framework. The Introduction for Management presentation goes into more detail about iterations, incremental development and comparisons with the traditional Waterfall methodology, such as when they were first introduced and their success rates.
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