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Critical points to be remembered for estimating activity resources or estimating activity durations are:

  • Accuracy of estimation improves if it is done basis WBS

  • Accuracy is also improved if estimation is done by the same person who does the work

The historical information provides critical insights for the process of estimation. Estimation will be more accurate if there are minimal or no changes in schedule, cost and scope baselines. A Project manager should manage the project schedule and project budget without any deviations to the schedule baseline. Integrated Change Control is used to approve or reject all change requests. Any issues related to schedule, cost, scope, quality, or resources can lead to change requests

A project manager's role is to analyze the project requirements, create new estimates basis inputs from team members and his experience with relevant projects, and resolve any differences to produce realistic objectives. Periodic recalculation of Estimate to Complete (ETC) is required to ensure adequate time, funds, resources, etc are available for the project. Project management plan should be revised as changes are approved and necessary work is completed. A non-acceptable project management practice is Padding. Any agreed-upon estimates must be met by the project manager. Estimates must be reviewed periodically to see if they are achievable and to check for padding and risks. Reduction or elimination of risks can result in decreased estimates. Providing accurate and feasible estimates is the responsibility of a project manager.

Estimate Activity Resources

The type and quantity of required resources are determined after the activities are sequenced. A resource could be an equipment, materials or people. Lack of resources is a common problem with all projects and hence, a project manager must plan and coordinate resources to avoid these problems. This results in getting two outputs:

  • Defined activity resources requirements

  • Resource breakdown structure (RBS)

Estimate Activity Durations

The Estimate Activity Durations process is to estimate how much time each activity will take. It is completed after defining and sequencing the activities and the type and quantity of resources for each activity are identified. Who should play a role of estimating these durations? Ideally, the estimators should be those who will be doing the work. However, the estimators are more often project team members who are more familiar with the work that needs to be done. The estimators need to have access to:

  • Activity resource requirements

  • Resource calendars

  • Historical data of the organization

  • Lessons learned about activity durations

  • Past project calendars

  • Defined scheduling methodology

  • Company culture enterprise environmental factors

  • Existing systems estimating softwares and productivity metrics


Padding undermines a project manager's ability of developing realistic schedules and budgets. A pad is an extra time and cost added to an estimate because the estimator does not have enough information. The potential need for time and cost arises when the project has many unknowns and information is not available to clarify the unknowns. This can be addressed with reserves through the risk management process. Risk management is an important process that converts uncertainties into identifiable opportunities and threats (risks). Estimators need to identify these risks and discuss with the project manager. These risks should not remain hidden. If many of the estimates are padded, the project will have an extravagant schedule and in this case, there is no need of creating a schedule or a budget. In actual real-world projects, the schedule and the budget are used as baselines against which project managers measure projects performance. Thus, these baselines should be as realistic and accurate as possible and project managers need to adhere to them. Padding is a poor sign of project management and it damages the reputation of a project manager.

Padding will not be required if:

  • A WBS is available with estimators

  • A WBS dictionary is also available with the estimators

  • Time and cost reserves on the project are identified through actual calculations

  • Risks and unknowns are identified

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