Calculating the need for resources
Most of us need to calculate the need for resources but the question is what you calculate.
One thing you can calculate is how much resources you need to complete a task. The first question is of course what do you mean by completing a task. If you’re working with software development, is it the coding, or does it include all the things you need before and after the coding (branching, getting to know the code, writing tests, merging, validating test environment) and does it include stuff that other people do. Another question is if you say something takes 10 days, do you mean 10 days of actual work or do you mean days between you start with a task and when you end the task, the latter concept is what we call Duration in Microsoft project.
In other words you need to know
* The definition of done
* Decide if you calculate Duration or Work
The next thing is that you need to start thinking about the difference between cost of delivery and cost of creating. Lets say you have a task which takes 40 hours of hard labor to complete. Lets say your resource actually completed the task in 40 hours. But chances are great that he will bill you more than 40 hours. People take breaks, the help other resources with their tasks, they do other stuff. Do they report these side things on your project? You bet! Imagine the opposite! Two resources are working on different tasks but on the same project. First one of the resources want a second opinion from his team mate. So he strolls over and they talk things over for 15 minutes. Would you want all resources keeping track on stuff like that. This is one of the reasons we want team rooms but it also gives us a situation when tasks cost more than the cost of their delivery.
As we are budgeting our projects, I must surely keep this in mind. In my budget, I must take into consideration that this happens so even if I use the scenario that 60% of time is spent on tasks, I need to calculate that they work 100% anyway. So I need to take into consideration:
* The number of hours tasks take
* The number of hours tasks bill the project
In other cases, thing become more complicated. Take the product owner role. That person should sit 100% of his time with the team but he doesn’t have to work 100% on project tasks. He can do other stuff in the team room (as long as he can be pulled from these tasks whenever someone needs help and that the other stuff doesn’t bother the other team members). If you do have a product owner who works 100% in the project that is perhaps more of a warning sign: you might have a product owner proxy or someone who’s not involved in everyday business work.