Best Practices

Now that we have an overview of the estimating techniques and methods that are available to us, and we have a feel for the estimating mistakes that are commonly made, let's review the estimating best practices of successful organizations and projects.

• Estimating should be based on the work breakdown detailed in the WBS.
• Estimating should be performed (or approved) by the person doing the work.
• The work estimates for lower level WBS items should be less than the standard reporting period for the project (typically one or two weeks).

  tip

  

  Estimating should be performed (or approved) by the person doing the work.

  The two main reasons: more accurate estimates and higher commitment levels to the project.

   

  As discussed in Chapter 6, if the work estimate is not less than this, it is a good sign the task needs further decomposition.

• Estimating should be based on historical information and expert judgment.
• Estimates are influenced by the capabilities of the resources (human and materials) allocated to the activity.
• Estimates are influenced by the known project risks and should be adjusted accordingly to account for those risks.
• All bases and assumptions used in estimating should be documented in the project plan.
• When asking an SME for an activity estimate, make sure to provide the following whenever possible:
  • Project definition document (context, approach, assumptions, constraints)
  • WBS
  • The applicable standards, quality levels, and completion criteria for the work package
• When asking an SME for an activity estimate, make sure to ask for the following at a minimum:
  • An estimate range (not just a single value).
  • Factors driving that range
  • Assumed resource level, skills and productivity
  • Assumed quality level and acceptable completion criteria
• Estimates should be given in specific time ranges.
• For managing high-risk projects, the following estimating techniques are recommended:
  • Use of phased and bottom-up estimating techniques
  • Use of the average weight and/or team consensus estimating methods
• For high-risk projects where the organization lacks significant previous experience or process knowledge, consider outsourcing the planning phase as an assessment engagement to an outside firm.
• A project's time and cost estimates should be based on project needs and not dictated by senior management. The project manager should work with senior management to reconcile any differences.
• Reserve time (contingency, buffer) should be added to either the project schedule or to individual activity duration estimates to account for the level of risk and any uncertainty that exists.
• Historical information is vital to improving estimates. If you don't measure actual performance, you will not have the feedback to improve estimat ing accuracy.

I have no doubt that these last two guidelines are common, everyday practice in your "real-world" experience.

A clear example of why leadership, negotiation, and communication skills are so important for project managers.

The Absolute Minimum

At this point, you should have a solid understanding of the following:

• It takes time and money to develop accurate estimates.
• Any estimating technique will improve results if it is used consistently by leveraging lessons from the past.
• To get science in the process, estimates must be compared to actual performance.
• Multiple estimating techniques can be used together. The art is knowing when to use which technique and knowing how much accuracy is required for the business decision at hand.
• Many variables beyond the control of the project team, such as changing specs, team turnover, and failed technology, can invalidate original estimates.
• Project managers should never work independently when making estimates.
• Organizations must make a conscious effort to establish rigor and procedures to estimating to improve accuracy over time.
• All stakeholders are responsible for estimates.

The map in Figure 7.4 summarizes the main points we reviewed in this chapter.

Figure 7.4. Estimating the work overview.