Sunday, February 10, 2008

Estimating Activity Duration

One thing you can't afford on a project is wasted time. Time wasted on a project will affect both the budget and the schedule. Fortunately, proper planning and accurate activity duration estimates can be used to keep your project on time and within budget.

Project managers use activity attributes to select and sort the activities that comprise a project. They look at all aspects of a project before determining the project schedule knowing that a "missed" or inaccurately estimated activity can drastically alter the project schedule.

Activity lists, which describe all the activities to be performed on a project, are used in estimating the duration of project activities. Resource requirements that detail the people, equipment, and materials needed for a project are also used as inputs in this process.

Activity duration estimates are quantitative assessments of the likely number of work periods that will be required to complete an activity. Activity duration estimates give project managers a range of possible results.

Project managers can determine a timeline for a project from the range of possible results. This range can be an indication of the number of work periods or the probability that the activity will take as long or longer than expected.

Sam is a project manager for an aerospace company. He is using activity duration estimates as an input to project schedule development. Sam has estimated that assembling the wing will take at least 8 days, but no more than 12.

There is a 15 percent probability that the assembly will take more than 12 days, and an 85 percent probability that it will take less than 12 days.

Since there is a high probability that assembly will take less than 12 days, the project manager will schedule 10 days for this activity.

While activity duration estimates help project managers determine how long activities will take, activity attributes also play an important part in selecting and sorting the given project activities.

Activity attributes are important because they enable project managers to select activities and sort them into convenient groupings. Project managers use these groupings to find out information about a given project. Activities exhibit three types of attributes: responsibility, geographic area, or building, and activity type.

The responsibility attribute refers to who will perform the work. The geographic area or building attribute refers to where the work will take place.

The activity type attribute refers to whether an activity is grounded in specific details or is based on a summary of events.

Activity duration estimates help project managers determine the likely number of work periods an activity will take to complete while activity attributes are important for sorting and selecting project activities. Both inputs are essential in planning a project so that it remains on time and within budget.

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