Decomposition

Decomposition is a technique used to divide the scope and or the deliverable in to small components where one should be able to manage it. When we divide the scope, we arrive at the work package. Work package is the lowest level of work breakdown structure. Further this work package will be decomposed to activity level.

Now the question is what is the meaning of manage? Manage means one should be able to estimate for schedule, cost and track the same. So the level of decomposition differs from project to project based on complexity in terms of effort. Typically 8/80 rule is used in general. The meaning of this is no work package should be less than 8 hours and no work package should be greater than 80 hours. So divide the scope in such a way that the work package should be in the range of 8 hours to 80 hours.

Decomposition can be done using box type or using tools like MS Project. Engineering projects uses ISO standards for decomposition. It is organization specific.

Decomposition technique is used under two processes. One in Create WBS and the other is Define Activities.