Comparing Schedule Snapshots

I like when people post old photos on social media, but especially the “then and now” pictures.  My favorite then-and-now pictures are when the people in the current picture wear similar clothes or attempt to strike the same pose as they did in the past. It’s fun to compare the images, noticing what’s different and what’s the same.

Not as much fun? Comparing snapshots of project schedules. This is a difficult and imperfect process. Why is this?

What You See

A project schedule is typically an extensive dataset. The schedule captures:

  • Performed activities.
  • Logic — how the activities are related to each other, including lags and leads
  • Resources — people, materials, equipment, etc.
  • Calendars — these are composed of the working and non-working days. There can be several calendars in play.
  • Constraints — rules about when activities must start or finish.
  • Expected durations.
  • Calculated dates.

A schedule comparison tool like Oracle Primavera Claimdigger (now a feature in Primavera P6 Visualizer) shows you the differences between schedule snapshots. The first thing you notice: the output is also a massive set of data that must be inspected and analyzed and explained. Your comparison work has just begun.

What You Don’t See

You don’t see what was never recorded. In photographs, you only see physical changes. You don’t see how they are different as a person, what they’ve learned, how they’ve grown, etc.

Similarly, changes in the schedule don’t reflect all of the changes in the project. Sometimes things happen in the project that aren’t indicated in the schedule. Sometimes the schedule is unable to indicate things that occur in the project.

You can see the “what” — the actual change between the snapshots. But you don’t typically see:

  • Who made the change, or when the change was made.
  • Why the change was made.
  • How the change was approved.

Project scheduling tools weren’t designed to record these things. Even if you had a system that recorded this information, your large dataset problem would be significantly larger.

We want to make your work a little easier and less stressful; it’s one of our core values as a company. So we created a schedule analysis tool that offers excellent schedule comparison features, and we’re currently working on new technology that could be a quantum leap forward. So stay tuned and keep an eye out for more details soon!

Before You Perform a Time Impact Analysis . . .

Many organizations, as they are considering the impact of a considered change to a project, perform a Time Impact Analysis (TIA).  A time impact analysis is a scheduling technique that models the change being considered and its impact (cost, time, resources) on the schedule.

Any article you read on performing a TIA stipulates as a requirement that your schedule must have a valid critical path. 

But what does “valid” mean?

In this context, “valid” means high quality.  Are the activities linked together properly?  Are constraints being used properly and only where necessary?  Are relationship types, lags, and leads being used properly?  Is there hidden trouble (e.g. negative float) that isn’t being addressed?  Does the schedule have the proper level of detail?

All of these questions help assess whether the critical path can be trusted.

As the Russian proverb made famous by President Reagan goes, trust but verify.  Large corporations are required to have a system of internal controls for their finances.  At Steelray, we believe that they are needed for project schedules as well.

Does your organization have internal controls for schedules?  Let’s talk!