Schedule control deals with analyzing the progress being made on project tasks based on the planned start and completion dates, in order to identify any deviation from the plan as early as possible. Deviation might be the result of a delay in starting the work on a given task or a delay in its completion and might actually be positive deviation. However, even in the case of a positive deviation it is still important to understand why it occurred and to respond to it by moving subsequent tasks up as much as possible.
A deviation in the schedule might be the result of changes in the project, a problem with the plan or a problem in task execution. Identifying deviations requires documenting the scheduled start and completion dates for each task in the project, as well as documenting the progress made on each task at various important points during the project. Then, at any given point in time, the status of a task can be compared to both the schedule planned for it and its status at these previous indicator points. The first important indicator point in any project is the project approval date, when the project baseline is created. It is this baseline that will then be used for evaluation and control purposes throughout the span of the project—unless the baseline plan is modified at some point, in which case the new baseline plan will be used instead for all evaluation and control purposes.
When a gap between plan and execution is identified, it is most important to identify and analyze any possible reason for the deviation, and then respond by:
- Narrowing the gap in cases of negative deviations;
- Replicating the gap for future tasks, if possible, and—in cases of positive deviations—adjusting the work schedule of remaining tasks by moving them up.
- If the deviation is the result of a planning mistake, then the work plan must be updated for all other tasks from this point on, so that this situation can be avoided in the future and these other tasks can be completed according to the revised plan.
If the deviation is the result of a problem in execution, the problem should be analyzed and corrected. If possible, the lessons learned should be applied to all similar tasks to avoid recurrence of the problem and to ensure that upcoming tasks are completed according to plan.
There are many and varied reasons for gaps between plan and execution:
- Unavailability of resource for task execution;
- Diversion of resources to urgent work outside of the project scope;
- Problems that crop up as a result of risks materializing, which then demand a response; etc.
An early understanding of factors that might result in deviations will aid in improving the schedule estimate from that point forward and preventing future problems by dealing with any emerging difficulties before they develop into severe problems. For example, early identification of a problem with a resource’s availability will enable replacing or reinforcing the resource or updating the task duration to reflect the resource’s actual availability—all before any deviations from the work plan have a chance to develop.
Data collection should focus on what still needs to be accomplished for the task to be completed by its deadline, rather than on the part of the work that has already been completed.
As the task is being worked on, it is possible to continue to refine the estimates for its completion. As a result, the expected completion date should be updated as work on the task progresses by revising how much remains to be done on the task until it is completed. Keeping this estimate up to date at all times will enable early identification of gaps between the work plan and its execution.
One should never assume that a task running ahead of schedule would certainly be completed on time. For example, if 80% of the work on a task is completed in 60% of the time allotted to it, this does not necessarily mean it will be completed ahead of time or even on time. Control activities should focus on evaluating the 20% of work still to be done and on deciding whether it can be completed in the planned, remaining time or not.
This evaluation includes analyzing all changes to the work plan on an ongoing basis and at least once each time that the work plan is updated. Periodically, differences between the updated work plan and the baseline plan should be noted. Significant gaps between plan and execution and consistent trends highlighting such gaps should be presented to the primary stakeholders and senior management in steering committee meetings, which should take place on a regular basis.