This blog post is one in a series of 10 based on a presentation I developed, “Top 10 problems new (and not so new) Project users have, and what you can do to ease the pain.” I first gave this talk at a Puget Sound PMI chapter meeting. I later gave an updated version of the talk to my local chapter of the MPUG Project User Group. As you might expect, at the PMI meeting the discussion tended more towards the broader project management issues, while at the MPUG meeting more towards specific features in Project. In fact at the MPUG meeting I had my computer projecting and we played around with Project features that related to some of the issues I brought up.
Top Ten List
In the process of writing the Project Step by Step books (starting with the 2000 edition and continuing through the current edition) with my co-author Tim Johnson, I observed first-hand some of the problems Project users encounter. Some of these problems are straight-forward gotchas in the software, but many common problems were really about how people define, understand and practice project management. In this and the other posts in this series, I’ll guide you through each of the top ten problems new or inexperienced project managers encounter, and what you can do to help identify and address these problems.
Problem #7: Don't distinguish work from duration
Project measures both duration and work values in increments of time, but duration gets a lot more visibility in the Project UI. In fact work only steps into the picture when you assign a resource to a task, and even then you need to dig a little to see work values. When you assign resources in your project plans, you may need to clearly distinguish the amount of work the resources are scheduled to complete from the duration over which the work will be performed. It can be a subtle difference but one you ignore at your peril.
Duration values are pretty prominent in the Project interface. In the default Gantt Chart view, Duration is the column just to the right of the Task Name column. As I said above work isn't even calculated until you assign a resource to a task. When you do, Project calculates work as duration times assignment units. This is the so-called scheduling formula: W=D x U.
What's Your (Task) Type?
At least, that's the scheduling formula for a task of the fixed-units type. Any task (other than a summary task) can be a fixed-units, fixed-duration, or fixed-work type. The default is fixed-units, so we'll stick with that type in this post.
Consider if you will my initial task list:
TIP Click the screenshot image to see a larger view.
You can't directly see work values in the Gantt Chart view, but take my word for it that the absence of assigned resources means that there are as-yet no work values associated with these tasks.
After I assign resources, you still can't directly see work in the Gantt Chart view's default Entry table, so we'll switch to the appropriately named Work table:
All Together Now: Work, Duration and Units
The Work table shows us work per task. But being the Project zealots that we are, we really want to see all three variables of the scheduling formula: work, duration and units. Right? One way to see this is to show the Task Form in a split view:
Now, for whatever task is selected in the Gantt Chart view in the upper pane, I see details in the Task Form in the lower pane.
The Task Form is an old, old part of the Project interface; it's like the garage that was neglected in the massive house remodel that spiffed up all the other rooms in the house. That's OK, it's a pretty functional view just the way it is. Here in the Task Form I see the essential details for a task; consider task 2 for example. With just the one resource assigned at 100%, the scheduling formula for this task is:
240 hours of work = 6 weeks of duration x 100% assignment units
Let's convert that to consistent units of time, starting with the Work value:
240 hours of work, at 8 hours per day (the default) = 240/8 = 30 working days.
Now let's convert Duration:
6 weeks, at 5 days per week = 6 x 5 = 30 working days.
So put it all together for:
30 working days of Work = 30 working days of Duration x 100%.
Twice the Resources, Twice the Flavor
With just a single resource assigned to a task at 100% units, duration will always equal work (assuming no customized project calendar or resource calendars are used). Where you may need to watch work and duration more closely is when you've assigned multiple resources, as with task 3 for exmaple:
For this task, the scheduling formula works out to be:
160 hours of Work = 2 weeks Duration x 200% assignment units
or
20 days of Work = 10 days Duration x 200% units
So when someone asks us "Hey, how long is it going to take to develop the production boards," we can answer in a few different ways:
"Two weeks!" (meaning 10 consecutive working days, interrupted by nonworking weekend days)
"160 working hours!" (meaning 160 person-hours, in this case being completed by two full-time resources working in parallel)
"As long as it takes!" (meaning you just can't rush good production board development)
If you assign a single resource at less than 100% units, you also see a difference between duration and work. In all cases though, Project keeps the scheduling formula true.
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.
The scheduling formula and task types
- Project 2007 Step by Step: "Changing Task Types," pg. 156.
- Project 2003 Step by Step: "Changing Task Types," pg. 140.
Task Form view and tables (Entry, Work, etc.)
- Project 2007 Step by Step: "Exploring Views," pg. 23.
- Project 2003 Step by Step: "Exploring Views," pg. 15.
###
Comments