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Projects Comparison based Estimation Model  
 
For further details you can download these references:  MS Word document.          MS Powerpoint Presentation.
 

While estimating new projects, comparisons are made with full or parts of the projects directly or indirectly using formal or informal means. Projects Comparison based Estimation model as implemented by RASS Estimate assumes that the project being estimated is similar to or a repetition of a previous project with respect to project life cycle, the type of tasks executed and the environment. It is also assumed that only the size and the complexity of the tasks may differ. There may be some additions and deletions of the tasks. The tasks size and complexity of new project are adjusted by a group of domain experts for modifying the base estimates. The base estimates should either come from actual measurements or experts opinion based. Projects Comparison based Estimation model has some similarities with the Extended 3-Points based Estimation model and is used as an alternate to the 3-Points based Estimation models. Estimators must review these models and decide which one to use.  The following are the main features of this estimation model.

  • Estimate the full project or part of the project
  • Creating the Work Breakdown Structures (WBS).
  • Provision to create Standard WBS Components (SWC) that can be used to assemble a new WBS. Here the concept of similarities is applied at SWC level rather than at project level.
  • Tasks' relative Size and Complexity are applied to task's base duration to calculate the tasks' estimated duration
  • Assign full and partly loaded resource while creating SWC. If required modify the resource assignments during the process of estimating.
  • Use of outsource profiles to estimate the outsource cost.  Outsource Profiles are defined and maintained centrally
  • Using Critical Path method to calculate project duration or impact on project duration if only part of the project is estimated by this method
  • Combining of duration estimates with duration estimates from other estimation models used by the project
  • Reports based on integrated estimates from all configured models as well as individual model
  • Preconfigured generic project profiles to tailor new estimation projects to reducing the model configuration tasks to minimum
 
 

The graphics on the left side shows high level users' view of this estimation model.

Creation of Work Breakdown Structure (WBS) that represents the complete scope of estimation work is the starting point.  WBS is created using the tasks and artefacts from the available Standard WBS Components (SWC) or from a similar project estimated previously. Once the WBS is in place, tasks relative size and complexity factors are applied by the domain experts to get the expected estimates, then resources assigned, tasks on critical path identified and Outsource Profiles are assigned to tasks to finalise the estimates.

The whole process is systematic and straight forward. You can create Standard WBS Components (SWC), store and use them to rapidly build a WBS. This model can produce reliable estimates very quickly.

You might have notice that the conceptual view shown here is a closed one. It means that you can reuse your historical estimates or create SWCs and store them and use when required. This is the primary success point of this model. Therefore, more you use this model, more SWCs will be available and it will be faster to estimate.

 

The following is a sample of the Estimation sheet that RASS Estimate has implemented for Projects Comparison based Estimation model.

  

 
For further details you can download these references:  MS Word document.          MS Powerpoint Presentation.