Schedule Adherence

Understand schedule proficiency by measuring how closely project execution is following your baseline plan. 3 min read.

General Principle

Intuitively, work not performed according to the logic of the baseline schedule often indicates activity impediments else results in rework. Whenever impediments occur (activities are performed relatively less efficiently compared to the normal project progress defined in the baseline logic), it is usual to find resources being shifted from constrained activities to other activities where they can gain earned value.

However, this results in a project execution that deviates from the original baseline schedule logic, which might involve a certain degree of risk. In fact, later activities are performed without the necessary inputs, which in almost all cases will result in a certain portion of rework. Based on these observations, Lipkeā€™s p-factor measures how closely project execution follows the baseline plan.


The p-factor is the ratio of the earned value corresponding to the baseline schedule divided by the total planned value at time instance ES. Since the numerator takes the minimum of the planned value at time unit ES and the earned value accrued at the actual time, the p-factor always lies between zero and one. Hence, the p-factor measures to what degree the earned value is accrued according to the baseline schedule (100% means a perfect schedule adherence).

p-factor calculation

Microsoft Project Demonstration

Shown below is a Microsoft Project demonstration project, which is adequately resourced and costed. This project has a schedule duration of 9-weeks and a cost budget of $150. The delivered project and the resulting tracking information, show a final duration of 11-weeks and an actual cost of $210.


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Schedule Adherence Results

Shown below is the p-factor results,

schedule adherence p-factor.PNG

Schedule Adherence Conclusion

The fundamental idea behind the p-factor concept lies in the detection of impediments or constraints whenever resources are used in an inefficient way resulting in an activity execution that lags the ES performance. This inefficiency, expressed by the p-factor, results in a correction of the accrued earned value by including the risk of rework and calculates the effective earned value, EV(e).

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