An out of sequence activity is an activity that is worked in an order other than how it was originally planned. When you build a schedule with relationships, you’re not only doing so to enable the tool you’re using to calculate dates, you defining the sequencing of those activities involved in the relationship. For example, if you look at the schedule below in Figure 1, there are two activities linked together with a Finish-to-Start (FS) relationship. By connecting these two activities together like this you are saying you plan for the second activity to start only after the first activity is finished.
There could be many reasons you are planning the activities this way. Task B might require the product from Task A to be complete before you can start the work, for example, you have to have a foundation before you can start putting up walls.
Maybe Task B will be easier to do if Task A is complete. Maybe its just the order you think makes the most sense when you’re putting your project plan together and by using relationships you can allow the tool to generate the start and finish dates. Whatever the reason, the relationship captures an assumption about how the work will be completed at the start of a project and that is perfectly valid to do.
Those activities will be considered out of sequence if they are progressed in a way that does not conform to the relationships. In the screen shot below, Figure 2, of the statused schedule you can see that Task A is still in progress, but you have already started work on Task B.
In other words, you are doing the work differently than you thought you would when you planned the project. There could be many legitimate reasons you are executing the project this way. Maybe Task A was taking longer than you thought and to keep on schedule, you needed to start Task B. Maybe a key resource for Task B became available and you wanted to take advantage of that by getting started on Task B.
In other words, “stuff” happens when you are working on a project and odds are you will not execute the project exactly as you had planned before it started. This can occur on any relationship type, not just Finish-to-Start ones. You may finish the second task in a Finish-to-Finish relationship before the first task is finished or start the second task before the first in a Start-to-Start relationship.
We would all agree that you are not always going to execute work exactly as you planned, but the question is what should you do about it when it shows up as out of sequence activities? The answer depends on why you are executing the tasks out of sequence and why the assumption (remember a relationship is an assumption of how you plan to execute the work) is no longer valid. There are a variety of reasons why it makes good project management sense to execute tasks out of sequence, some of which are listed in the paragraph above. If that happens, you need to be aware of it and also understand the implications of doing so.
When an out of sequence activity is identified you need to go back to the original assumptions used when the plan was put in place. Remember, the original relationship represents an assumption about how the work will be executed. Key here is, does changing the way the tasks are executed introduce risk into your plan.
If your original plan called for finishing all of the development before you started testing then you could probably rationalize starting the testing task (Task B in our example above) before the development (Task A) was complete. You could start testing what has been developed without waiting for everything to be complete. If your Task B was to start attaching the wings to the fuselage and the wings are not done, you might have a problem.
You will need to look at each situation and determine if new logic is needed or if you should stop work on the out of sequence task until the original logic can be honored. So it’s not necessarily bad that you have something out-of-sequence, it’s just bad if you do not know it is occurring and do not take the necessary steps to deal with the situation.
The Out-Of-Sequence metric, along with metrics like relationship validations, bottleneck identification, risk hot spots, task density, duration validation and others are all valuable inputs to maintaining a quality, reliable schedule. Reviewing these metrics regularly throughout the life of a project ensures your schedule will provide you and the project stakeholders with the most relevant information to act on, and knowing is half the battle.
Ten Six is offering a free ’Pulse Check Schedule Assessment’ which looks at 10 key schedule health metrics and provides initial analysis around the results. The metrics are focused on areas that have proven to be weak spots in schedule health over time and represent areas that the project should review. Learn more here and call us today!