For a properly prepared WBS (Work Breakdown Structure), the following guidelines provided in PMI's Practice Standard for WBS should be considered during the development of a WBS

● The set of child WBS elements into which a parent element has been decomposed should include all of the work contained in the parent, fulfilling the WBS's 100% Rule.

● A coding scheme should be used for all WBS elements which clearly represents the hierarchical structure of the WBS.

● Decomposition of all parent elements of WBS need not be of the same depth. Some parts of the WBS will need to have less or more detail than others.

● All work packages need not to be at the same level.

● The WBS development process should:


● Be iterative

● Be reviewed as well as revised just as the rest of the project planning process progresses.

● Provide a space for flexibility, specially when the scope of the project effort can change.

When developing a WBS, the following basic principles should be followed:


● Every WBS element represents one intangible or tangible deliverable. Intangible items include information/communication, training, administration, procurement and process management. Tangible elements are like wall, machinery, house, painting, a book, electrical/civil works, etc.

● Deliverables are distinct and unique.


● Deliverables include both interim and final deliverables that are required to create the final desired results.


● All important reporting processes such as weekly/monthly reports, review meetings,  test reports are included in WBS.


● Every project deliverables should so unique, ensuring no duplication in the outcomes of the project or end-products.


● Accountability for each work package should be assigned to a one team member or a subcontractor. In case, this seem impossible, reconsider whether or not
the work package can be further decomposed.

● Every element in WBS representing externally committed or subcontracted deliverables should directly correspond to associating elements in the subcontractor’s WBS.


● Deliverables are logically decomposed to the level that represents how they will be managed and produced.


● All WBS elements should be compatible with company's and accounting structures.


Also read: Guidelines for organizing WBS elements into the WBS hierarchy

Reference: Practice Standard for Work Breakdown Structures

Many new planners ask this question 'What is resource leveling'? Well, when we are developing the schedule, we are sequencing the activities. Moreover,  we are entering duration and also assigning resources onto the activities.  Now, while we are performing all these activities, our focus is generally to sequence activities based on our task dependencies (mandatory or discretionary).

Once all activities have been entered, their relationship set and resources assigned, we may end up developing a schedule where some of the resources are over allocated and some under allocated.  Now, we perform resource leveling to make sure all resources are leveled.

How to Level an Overallocated or Underallocated Resource?

Resource can be leveled by many ways, and depending on the situation, priorities and requirements, we choose any of the best suitable options:

  • Reduce Resource’s Hours/Day.
  • Stagger work hours over one or more activities.
  • Increase Activity’s duration.
  • Change Activity date to a date when resource is available for more time. 
  • Add more resource to the activity, and reduce hours of the overallocated resource.
  • Increase availability of the resource.

The planner will decide the best suitable option(s) and until all the resources are not leveled, the project should not go onto the execution phase.

Analogous estimation technique:

It is a comparison technique where we look at a similar activity performed before. If more data is available, the better the estimate will be.

Parametric estimation technique:

Parameters from previous similar activity is taken. E.g. Previous activity took 5 days and it had 3 resources working on it, 10 hours daily. This method is more accurate then analogous estimation

Three-point estimation technique

It is used when there is a great deal of uncertainty about duration. We use these parameters and use in the formulas below.


M = most likely | O = optimistic | P = pessimistic | E = expected duration

  • Triangular Distribution:       E = (P + M+ O) / 3
  • Beta Distribution (also called PERT - Program evaluation and review technique):      E = (P + M(4) + O) / 6


Beta Distribution is preferred in cases where we have a lot of historical data.  When there is no historic data, only with guesses, use Triangle Distribution.

Using these duration estimation techniques, you can get near-to-accurate duration value. It is much better than just guessing a wrong duration, which will negatively effect the project end date

Page 1 of 2