New project schedule validation – know it can happen

Your schedule is your path. How good is it?

Many project managers have no real idea of how to validate their initial project schedule. How do you know that this schedule can get you to your ultimate goal?

I won’t try to make this up.

The Defense Contract Management Agency (DCMA) has developed 14 quality checks for validating schedules. This agency manages contracts for the Department of Defense here in the U.S, working with suppliers to manage their projects for the Federal Government.

For those of you who like to “geek-out” on this type of information, see the DCMA’s Earned Value Management pamphlet, section 4.

All of the items that the DCMA references are important. For the sake of this post, I’m going to talk about the ones I use most often in my schedule development. If you have other thoughts, feel free to mention them in the comments below.

Schedule metrics

There are metrics that project managers need to run on their schedules before they can use some of the quality checks. These metrics include:

• Total lower level tasks (excluding summary, subproject, milestone and zero baseline duration tasks)
• Completed tasks
• Incomplete tasks
• Baseline counts
• Relationship count

For the sake of brevity, let’s focus on new schedules that have very few completed tasks. We’ll talk about total lower level tasks and relationship counts. Here are the quality checks I run on a new schedule. Once I have these pretty close, I’ll go down through the entire quality checklist.

Project Schedule Quality Checks

Logic checks

Look through your schedule. All supporting tasks that should have a predecessor and a successor. Don’t set successors or predecessors for Summary tasks. A good schedule doesn’t have more than 5% of its tasks missing logic.

Leads

There should be no tasks with negative leads in the schedule. For example, task 1 starts on 6/1, task 2 should not start on 5/30. Negative leads mess with your critical path calculations and shouldn’t be allowed.

Lags

Avoid having any lags in the schedule. For example, if task 1 starts on 6/1 and goes through 6/5, task 2 should start on 6/6, not 6/10 or 6/15. A good schedule has fewer than 5% of its tasks with lags.

Sometimes lags are unavoidable, particularly if you’re waiting on deliveries or want to get something completed because a resource is available.

Relationship types

The majority of your tasks should have a Finish-to-Start relationship. If less than 95% of tasks have a Finish-to-Start, work on those tasks that have a different relationship so that you can use a Finish-to-Start. You want your schedule to flow logically and Start-to-Start and Finish-to-Finish break up your flow.

Hard constraints

When hard constraints are used such as Must Finish On or Must Start On, you create much more work for yourself figuring out why critical path calculations aren’t correct and why, when you change a date, nothing seems to move out correctly. Save yourself time and grief and avoid these. DCMA says that no more than 5% of tasks should have hard constraints.

Float

High float, more than about 40 working days can be the sign of a missing predecessor. In addition, any task that has a duration of 40 days or longer probably should be broken up into smaller tasks. Negative float should be purged out of the schedule altogether.

The critical path test

To run the critical path test, add an intentional delay of 500 days onto the critical path. Then run the critical path calculations. If your end result is a 500 day delay, your schedule is pretty good. If you’re over or under that 500 days, you may have missed a predecessor or successor somewhere, you have a hard constraint that is causing trouble or a relationship set up that is corrupting the path, like a Finish-to-Finish.

Go back and double-check for these potential trouble spots.

Next week, checking your schedule once the project has started and you have tasks that are completed. We’ll add in resource and baseline checks.

What other checks do you do on a new schedule? Let us know in the comments.