Once you’ve properly mapped out the activities necessary to carry out the project, you’re ready to move to the next step in scheduling - estimating how long it will take to get the work done. The most common process is to utilize two methods to do this.



The first way to characterize the length of an activity is effort. Effort is defined as the number of labor hours that task performers will be working on a given activity. You might think of it as the amount of time they’ll be charging to your project.



The second way to characterize the length of an activity is duration. Think of duration as the window of time within which the activity is to be completed.



Here are some key points about the duration of an activity:



1. Duration is the length of time that you would use for an activity when you place it on your project schedule.



2. Duration is derived by considering the effort required to complete an activity, then making appropriate adjustments for:

 

 





     
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  • The quantity of resources assigned to work on the activity (and how efficiently they can work together at the same time)




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  • The general availability of the resources (half-time?  quarter-time? 10%?)




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  • Specific periods of inactivity or unavailability (vacations, site shutdowns)




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  • Weekends, holidays




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  • Number of hours assumed in each work day




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Although duration appears to be a calculated quantity, you should think of it as more of a negotiated figure and a kind of “meeting of the minds” than as a calculation. When you and a given task performer agree on a duration for an activity, it almost represents a contractual relationship - the task performer is promising to finish the task within a window of time and you are accepting that estimate.



In order to properly manage your project, you will need to understand, quantify, and track both effort and duration. Since effort represents the time people are charging to your project, it relates directly to cost estimating, budget preparation, and cost control.  Duration relates directly to schedule estimating, schedule creation, and schedule control.