How to assign resources to tasks

- [Voiceover] Suppose you've put the project tasks in sequence, and estimated their durations. You still won't know what your schedule really looks like until you know how many people you get to work on each task and when they're available. Let's take a look at how tasks change due to resource assignment. Duration is the length of time between when a task starts and when it ends. Work, also called effort, is the number of hours or days someone works on a task.

If you get more or fewer people than you planned for, your task durations will change. Let's see how that works. Suppose you estimated that the conference center equipment installation is going to take five people four days to complete. How much work is that? It's eight hours per day, per person, so that's 40 work hours per day for four days, or 160 work hours. What if you only get four people? How long will the task take then? Get your calculator or abacus out and follow along.

There's still 160 hours of work, but now the team of four can only work 32 hours each day. If you divide 160 hours by the number of hours per day, that's 32, you get a new duration of five days. The work stays the same, but the task duration varies. The same calculation applies if someone switches to half time work instead of full time. Because you divide the amount of work by half the number of hours each day, the task will take twice as long.

On the other hand, if you get more people, the duration of the task decreases. Say the IT vendor can give you eight people. There's still 160 hours of work, but now the team of eight works 64 hours each day. If you divide 160 hours by 64, your new duration is two and a half days. Then again, some tasks don't get shorter no matter how many people you assign. Meetings are the classic example.

A four hour meeting is four hours long, whether three people attend, or 10. When assigned resources are available also affects when work occurs. For example, your schedule might show the equipment installation starting on February 9th. However, the IT vendor is wrapping up another project, and the team won't be available until February 18th. Guess what? That's right, you have to delay that task in your schedule to reflect when the resources are available.

When you assign resources to tasks, you finally get a clear picture of when work occurs in your project. To see more about how resource assignments affect your project's schedule, see my course, Managing Project Schedules.