Carl Chatfield: Top 10 Problems, #8: Overestimate resource capacity

Carl here. ProjHugger is for Microsoft Office Project newbies, enthusiasts, and zealots. I publish new posts every Monday morning, but you can add comments any time. This week’s ProjHugger post continues the “Top 10 problems new (and not so new) Project users have, and what you can do to ease the pain” series. This week:

#8: Overestimate Resource Capacity

For many projects, the capacity of work resources is a critical factor in the success or failure of the project. Work capacity is something you should be able to accurately estimate, quantify, and manage throughout the planning and execution of any complex project. This is especially true for projects that are deadline-driven and requires highly specialized people to complete the work--many projects involving knowledge workers fall into this category.

Just what is work capacity? One way to think of it is as the ability of a person to complete tasks in a project plan, and quantified in working hours. So simplistically speaking one person working a normal full-time schedule for one week would have 40 hours of work capacity. 10 people would have 400 hours work capacity for the week.

I say this is simplistic thinking because when dealing with knowledge workers, it's rare that any one person is really able to spend all of their working capacity on known tasks within a single project plan. Think about your own work life. Let's say you do work a more or less predictable 40 hours per week. Do you ever take vacation days? Are you ever out sick? Take the occasional long lunch with a friend or extended daytime workout at a health club? All of these chip away at your work capacity. Of whatever time you really do have left, is that time booked against tasks in a single schedule? Multiple schedules? You can see how difficult it can be to accurately represent just one person's true work capacity. Now imagine doing so for your entire resource pool.

Smart People and Dumb Math

Here's an exercise I've seen some smart people who should know better go through, typically at the early planning stages of a project and while standing at a whiteboard. I paraphrase:

1. "Let's see, we have ten weeks to complete this project." (Carl wonders silently--really? Is the project driven by some external deadline?)

2. "And we've got five people to get this project done." (Again, really? Do these five people all know their work lives are to be dedicated to this project for the next ten weeks, or longer?)

3. "OK, 40 working hours per week times five people" (Ack! Any holidays coming up? Anyone going to be out sick or on vacation?)

4. "Gives us, tada!  2,000 hours of resource capacity for this project." (Ho boy, that is the best of the best-case scenarios of capacity planning.)

Here's what gets captured on the whiteboard:

10 weeks, 5 resources, 40 hours per week
10 x 5 x 40 = 2,000
2,000 hours resource capacity

Happily, accurately measuring resource capacity is one project management challenge where Project can really help you. Starting from broadest to most specific features, let's see what we can do to improve our calculations. Let's start with this simple project plan: