Effort-Driven Tasks

An effort-driven task is one where the total amount of work required to complete the task is directly affected by the number of resources that have been assigned to it. In other words, the amount of effort determines the amount of work that can be done.

The effects of adding resources to an effort-driven task are determined by the task type:

For a task with a type of fixed duration, adding resources will decrease the unit values for any resource that is assigned to the task.
For a task with a type of fixed units, adding resources will shorten the duration of the task.
For a task with a type of fixed work, adding resources will shorten the duration of the task.

The best way to determine whether a task can be identified as an effort-driven task is to consider whether assigning additional resources to that task will result in an increase to the rate at which the task can be finished. However, many tasks should not be identified as effort-driven tasks. For example, adding a resource to a complex task may decrease the rate at which a task can be finished. The newly-assigned resource many need a ramp-up period or may need the assistance of a currently-assigned resource in order to understand the complexity of the task. In many instances, adding a resource may not result in more work getting done or in the task being finished sooner.

Let's use a simple example to illustrate how an effort-driven task can be used to shorten the duration of a task (and, in this case, the duration of the entire task plan). You are planning to purchase some new bookcases; the following tasks would need to be done:

#	Task	Task Details
1.	Drive to furniture store from home.	1 hour.
2.	Stop to fill up gas tank. Buy gasoline.	15 minutes; 10 gallons @ $2.50 per gallon.
3.	Purchase four new bookcases.	45 minutes; $100.00 x 4 bookcases.
4.	Drive home from furniture store.	1 hour.
5.	Assemble bookcases.	8 hours?. For a single resource, each bookcase will take an estimated 2 hours to assemble.
6.	Arrange bookcases.	30 minutes.
7.	Add books to bookcases.	4 hours?. For a single resource, each bookcase will take an estimated 1 hour to fill.

There are three tasks in this list that are candidates to be identified as effort-driven tasks: 5, 6, and 7. If three friends came over and helped to assemble the bookcases, arrange, and then add books to them, then the amount of effort for each of these tasks would increase and the duration for each of these tasks would decrease. For example, it takes 2 hours to assemble each bookcase. A single resource would spend 8 hours; four resources would spend 2 hours.

Tasks 1, 3, and 4 are examples of tasks that would not benefit from being effort-driven. For example, four people riding in the same vehicle cannot drive to and from a furniture store in less time than a single person can.