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Estimate Activity Durations Process: PMP Exam Guide

Estimate activity duration process

Activity duration is a significant input in a project’s overall schedule. Estimating activity durations prevents a project from unnecessary delays. The time assessed for each activity is a reminder to the project participants including its manager. 

What Are The Inputs Of The Estimate Activity Durations Process?

Apart from the risk register, management plan schedule, and RBS (Risk Breakdown Structure), there are seven inputs to estimate activity durations. 

Activity list

It is the most significant of all the inputs and must not miss out on any of the project’s identified activities. This provides a precise idea of the total number of tasks to analyze the time taken by each of them. 

Activity resources

Estimating activity resources is considered a separate process but it plays a vital role in determining the duration. Outputs of the former process are used as inputs for the ‘estimate activity duration’ process. 

Resource calendars

Unlike material resources, human resources can’t be available 24×7 during a project. Suppose a 50-hour task requires a certain number of individuals all of whom might not present on the same date on the calendar. So, different individuals have to be assigned for different dates depending on their availability. This decides the duration of each task. 

Project scope report

A statement declaring the constraints and assumptions related to a project is termed the ‘project scope statement’. It identifies if a particular task has to be outsourced and estimates that activity’s duration accordingly.  

OPAs (Organizational Process Assets)

OPAs provide information on the ‘estimate activity duration’ process in previous projects. They also contain details about the respective organization’s work culture. These documents easily detect if there is any peculiarity within the working patterns like shift working or overtime. That information is used to precisely estimate activity duration

Environmental factors

The work environment directly influences the task duration. For instance, if the project site is an oil rig then the participants will execute the operation following certain safety guidelines. This would affect the initially estimated time of the activity. 

Major Outputs Of The Estimate Activity Durations Process

Activity duration estimate is the main outcome of this process. Different tasks will exhibit different time frames for completing them. Techniques and tools of this process allow preparing duration estimate ranges for individual tasks. 

Secondly, project documents get updated too. Assumptions regarding knowledge, experience, and expertise are noted at the time of estimating activity durations. Activity attributes automatically change at the end of this process. 

Tools For Estimate Activity Duration 

The ‘estimate activity durations’ process is necessary to determine a realistic project completion date. 

Expert judgment

One who is an expert at a particular task must provide the duration estimate for that activity. So, any member of the project team can act as an expert depending on his/her potential and skill.

Analogous estimating

This is a technique of estimating activity duration by referring to the same task of a past project. One gets a clear idea if not fully accurate about how much time the same task could take in the new project. 

Parametric estimating

The project team members can integrate statistical data with references from earlier projects. This method uses duplicate parameters and data of a similar previous project for identifying the current project’s time and cost. Productivity rates of the equipment used in the old projects are gathered in this process for assessing the project’s duration. This technique assures better accuracy than analogous estimating and is more effective. 

Three-point estimates

This technique comprises three parts yielding three different kinds of estimates. These are:

  • Estimates of time and expense under normal circumstances.
  • Pessimistic estimate based on an overall negative assumption of occurrences.
  • Optimistic estimate assuming the entire project progresses as planned earlier. 

Reserve analysis

First, a schedule is established for each project task. Then the project manager adds contingency reserve to those schedules as a duration percentage. The project team manages schedule risks for preventing any further mishaps. 

How To Shorten The Project Schedule?

Finishing a project ahead of time saves energy and expenses, as well. Three methods are available for shortening a project’s schedule.

  • Reduce the timeline stated in an activity’s work scope.
  • Use more machinery and resources.
  • Enhance productivity.

In each of these practices, the project manager must engage every team member and other associated individuals. This will help in making proper decisions in every aspect of activity duration estimation. 

Realistic estimations influence cost distribution and project resource requirements, keeping them realistic, too. ‘Estimate activity durations’ is an ever-changing process. It continues updating with the operations of a project changing from time to time. 

This process takes every single project update into account such as safety issues, costs, resource procurement, etc. It is an all-in-all monitoring framework ensuring that the project meets no serious obstacles in its execution. Constant and effective alterations in different faculties guarantee a project’s success. 


Posted in Project Management

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