This week I don my inspector's cap to solve a mystery of why the resource overallocation flags disappeared.
Here's the story. An eagle-eyed Project 2010 Step by Step reader submitted a bug on what at first glance appeared to be a corrupted practice file. This reader observed that some resource we show as being overallocated in Chapter 10 of the book were not flagged as overallocated in his installation of Project. My coauthor Tim and I investigated the issue and discovered that the data file was indeed OK but there's a user-controlled setting that can effectively hide resource overallocations from you.
Before I reveal the solution to the mystery, let's review the basics of resource overallocation.
In Project, when you assign a work resource (people or equipment) to a task, you create work. This then enables Project's venerable scheduling engine to do what it does best--constantly and unerringly calculate work, duration, or units following the scheduling formula. The scheduling formula is a representation of how Project calculates work (or, depending on the task's type, calculate duration or units) based on the duration and resource units of an assignment:
Work = Duration x Units
You adjust the formula to solve for the other variables, for example:
Units = Work / Duration
Duration = Work / Units
I said above that task type affects the scheduling formula. Every task in Project is of one of three types:
- Fixed units (the default)
- Fixed work
- Fixed duration
In Project 2010 you can see a the type of the selected task on the Task tab, in the Properties group, Information command. Then in the Task Information dialog box, click the Advanced tab and note the value in the Task Type field. Here's one example:
When we say that a task is of the "fixed units" type, what we really mean is that Project won't change the task's assignment units values but will instead recalculate its duration value (if you change the task's work value) or Work (if you change the task's duration). You can also change the units values on the resource assignments, and Project will recalculate Duration. But Project will not change the units values of a fixed-units type of task.
Now let's cover the subject of resource allocation. If a full-time resource is assigned to, say, a 2-day task that is of the type fixed units, the scheduling formula for that task looks like this:
2 days Work (same as 16 hours) = 2 days duration x 100% assignment units
So far so good. But let's say a resource is assigned more work in a given time period than they have the capacity to do, according to their available time to do work (what we call max. units). If my single resource (we'll call her Carole) is assigned to task A at 100% units Monday, and Tuesday, and to task B at 100% units on Tuesday and Wednesday, she'd have the following daily work allocations:
- Monday: 100%, or 8 hours (all on task A)
- Tuesday 200%, or 16 hours (100% on task A, plus 100% on task B)
- Wednesday 100% or 8 hours (all on task B)
Carole is fully allocated on Monday and Wednesday, but overallocated on Tuesday. She has more work to do (twice as much, in fact) to do on Tuesday than her max. units allow.
As you can imagine, assigning resource (especially people resources) to tasks in complex schedules can frequently lead to resource overallocation problems. You might be able to remedy some overallocation problems by requiring some overtime work, by switching some assignments between resources (resource substitution), or reordering, splitting or delaying some tasks. These are all strategies a project manager can bring to the problem.
Now back to the mystery. The reader noted that when he viewed the Resource Usage view of the practice file for Chapter 10 of the Project 2010 Step by Step, some resources who should have been flagged as overallocated did not appear so. Here's the view this reader expected to see (and what we show on page 213 of the book):
Note the overallocation flag in the Information column next to Carole Poland. When I point the mouse pointer at this flag, I see the message "This resource is overallocated and should be leveled."
"Leveling" is what Project refers to as fixing overallocation problems, using some of the strategies I mentioned above. Leveling can be an action the project manager undertakes one overallocation at a time, or it can be a process Project runs at your request (via the Resource tab, Level group, Level Resource command). I've written previously about the challenges of expecting Project to solve resource overallocation problems without requiring some extension to overall project duration, or additional resources, or both. Your mileage may vary.
There's one other aspect of overallocation I need to explore, and it was indeed the root cause of our reader's issue.
In the Monday/Tuesday/Wednesday example from above, Carole is said to be overallocated on a day-by-day basis. This means that when our focus of time is per day, then clearly 16 hours of assigned work in a single day is too much for a single person. However, what if Carole is a knowledge worker with lots of independence and latitude about how she structures her working time, and task A and task B are her only assigned tasks that week? In that case, Carole has 32 hours of total work to do in a 40-hour workweek. When thought of not at the daily scale but weekly, Carole is not overallocated, but is in fact underallocated.
Now one caveat I have to mention is that there may be good reasons task A and task B need to be completed as scheduled--they may have important successor task deadlines looming, for example. That's an important issue but independent of the resource overallocation issue.
So when we talk about resource overallocation, we often mean daily overallocation (and indeed this is Project's default overallocation setting--more on this shortly). But we might instead focus on weekly or monthly overallocation (or go in the other direction--hourly or even per minute, for you micromanagers out there). This is an important parenthetical point to include in discussions about overallocations.
It turns out that the reader who surfaced the Project 2010 Step by Step issue may have been working with an installation of Project that used a different criteria of what resources to flag as overallocated (and there is such a setting in Project). The setting in question is Project-wide, not per-project. This means that the same overallocation setting applies to all schedule files I open in Project. That makes sense if I tend to work with schedule files that all relate to one organization, and the organization has a generally consistent approach to dealing with resource allocation issues. For example at my day job surrounded by highly autonomous knoweldge workers, nobody gets worked up at daily overallocations.
The daily default setting makes less sense however if I work with schedule files from a variety of organizations, or even with a schedule file from a self-paced tutorial like Project Step by Step.
Here's the setting in question: on the Resource tab, in the Level group, click Leveling Options:
Besides daily, the other time increments available here are per minute, hour, week and month.
Here's the practical effect this setting has. I can see that on April 16 and April 23, our resource Carole is assigned 9 hours of work each day.
Because our Project-wide setting is to look for overallocations on a day-by-day basis (the default setting). Project flags Carole as overallocated due to these and perhaps other days where her assigned work exceeds her maximum capacity of eight hours per day.
However, after I adjust the Leveling Option setting to look for overallocations on a monthly basis, Carole's overallocation flag disappears:
While Carole still has daily (and even weekly) overallocations, she is not overallocated at the focus of month.
It is important to note that there's no change to the underlying assignment data here. The only thing that has changed here is the threshold at which I want Project to flag overallocated resources.
So there it is, mystery solved. I refer to this type of issue as an "onion problem," because getting to the root cause of the issue requires some peeling away of layers and occasionally shedding a few tears.
Hands-on with Project Step by Step
To read more about this blog entry's subjects in the two most recent editions of Tim Johnson's and my Project Step by Step books, see the following cross-references.
Task types and the scheduling formula
• Project 2010 Step by Step: "Changing Task Types," pg. 158
• Project 2007 Step by Step: "Changing Task Types," pg. 156