Hi,

I got this comment from one of my Blog readers: “I’ve seen there is a bug on calculation of USE!
there are 2 conditions of fault:

a) fixed work,,, you change duration… nothing happens to resource % use
b) fixed Duration … you change work … nothing happens to resource % use BUT is not deeply true!!!

if you goes to “resource diagram” the % is recalculated,
I think something is missing in the code.
It’s a pity because for me the automatic calculation of use% was very useful!!!!”

Is this a Bug in MS PROJECT 2010 or MS PROJECT 2013? No, it is not. But it is confusing thing. Let me explain it to you!

First I will add one simple Task in My Project:

and I will add two Resources , as well:

Now I will assign both Resources to the Task:

and I will set up Detailed View:

and then:

and I will get:

Now suppose that my Task is Fixed Duration:

As you remember from my Previous Post, the Relation between Units, Duration and Task is: DURATION * UNITS = WORK

Now suppose that I change hours for John from 40 to 60, and for Mary from 40 to 20:

and I will get:

So let us look at the Magic Formula: DURATION * UNITS = WORK.

• For John: 5 days (5 days * 8 hours per day) is 40 hours * 100% = 40 hours
• For Mary 5 days (5 days * 8 hours per day) is 40 hours * 100% = 40 hours

Where is the Catch? It seems like a bug. It should be:

• For John: 5 days (5 days * 8 hours per day) is 40 hours * Units% = 60 hours, so Units% = 60/40 = 1,5 e.g.. 150%
• For Mary 5 days (5 days * 8 hours per day) is 40 hours * Units% = 20 hours, so Units% = 20/40 = 0,5 e.g.. 50%

Now I will use a Task Usage View:

and I will get:

I will add new Column: Peak!

and I will get:

So the Magic formula is: DURATION * (Peak) UNITS = WORK.

The same thing is if you use Fixed Work Task Type!

If you want some further and Detailed description please read this article:

http://blogs.msdn.com/b/project/archive/2010/04/29/assignment-units-in-project-2010.aspx

Regards!