Earned Schedule: Forecasting


Project Duration Increase from Rework



By Walt Lipke

Oklahoma, USA


The introduction of Earned Schedule (ES), as an extension of Earned Value Management, led to the discovery of schedule adherence (SA). With SA, project managers can observe how closely the project execution follows the planned schedule, by monitoring the Schedule Adherence Index (SAI). SA provides methods for identifying tasks that may have performance restricted by impediments or process constraints, and other tasks that may experience rework in the future. As well, calculation methods have been created, utilizing SAI, for determining the rework generated from performing tasks out of their planned sequence. Thus, project managers have facility to assess the cost impact of rework. Rework obviously impacts project cost, but it must, also, increase project duration. This paper takes another step in the evolution of ES. A method is developed for determining the duration increase caused by rework.


Earned Schedule (ES) has been in existence since 2003 [Lipke, 2003]. Over time ES has been recognized globally by inclusion in various standards for project management, Earned Value Management (EVM) and scheduling [PMI, 2011], [PMI, 2017], [ISO, 2018], [PMI, 2019]. As such, it is presumed the reader has a working knowledge of both EVM and ES. Thus, reviews of these management methods are not discussed. Should the reader require more background, see the PMI Practice Standard for EVM referenced previously, and the book Earned Schedule [Lipke, 2009].

The concept of schedule adherence (SA) is another matter; even now, it is not well known and is not prevalent in application. The concept was introduced in 2004 [Lipke, 2004], only a year after the seminal paper on ES. At that time, the idea of SA could not be taken up and readily applied. It depended upon understanding ES for which very few were aware and thus, certainly had no idea of SA.

With the general acceptance of ES as a recognized extension to EVM, it is timely to re-introduce SA and more fully utilize the management facility it offers. SA extends ES to project management methods for identifying tasks likely to be performance impeded or constrained and those having a potential of rework. As well, it provides methods for computing the portion of earned value (EV) that moves the project toward completion, termed “effective earned value.”

In 2011, the approach for forecasting the total cost of rework from lack of SA was developed [Lipke, 2011]. Having the ability to compute the cost impact of rework, in turn, provides project managers with a reason to increase attention to managing schedule performance and improving planning.

Although a facility has been available for calculating the schedule performance impacts of rework, it hasn’t been fully recognized, and therefore not employed. A recent paper presented SA derived schedule analysis methods, in an attempt to further propagate the application of ES and encourage greater project control of schedule performance [Lipke, 2020].

Even so, the application of SA from its introduction several years ago, primarily, has focused on the impact to project cost. This article provides a review of SA, and then presents a method for computing the project duration increase caused by the accrual of rework. As the reader will discover, if he/she is applying SA analysis, it is a simple matter to compute the increase to project duration.

Schedule Adherence

Figure 1 provides a visual for discussing the concept of schedule adherence. A schedule is represented above the EVM plots of the Performance Measurement Baseline (PMB) and the Earned Value (EV) accrued. The point on the PMB where the Planned Value equals the EV accrued is identified. The duration to that point is the portion of the Planned Duration earned, i.e., Earned Schedule. The vertical line drawn from the time axis through the PMB intersection and then upwards through the schedule identifies the tasks that contribute to the PV at that point in time. Thus, we can know what should be accomplished for each task. The darkened areas indicate the EV in each task. As can be seen the EV does not align with the PV of the schedule.


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Editor’s note: Second Editions are previously published papers that have continued relevance in today’s project management world, or which were originally published in conference proceedings or in a language other than English.  Original publication acknowledged; authors retain copyright.  This paper was originally presented at the 15th UT Dallas PM Symposium in May 2023.  It is republished here with the permission of the author and conference organizers.

How to cite this paper: Lipke, W. (2023). Earned Schedule: Forecasting Project Duration Increase from Rework; presented at the 15th University of Texas at Dallas Project Management Symposium in Richardson, TX, USA in May 2023; republished in the PM World Journal, Vol. XII, Issue VIII, August.   Available online at https://pmworldlibrary.net/wp-content/uploads/2023/08/pmwj132-Aug2023-Lipke-earned-schedule-forecasting-project-duration-increase-from-rework.pdf

About the Author

Walt Lipke

Oklahoma, USA


Walt Lipke is a professional engineer with a master’s degree in physics. He is a graduate of the USA DoD course for Program Managers. He retired from federal service with over 35 years of experience in the automated testing of avionics. Lipke is the creator of Earned Schedule (ES). He has published over ninety articles on the method, as well as two books, Earned Schedule and Earned Schedule Plus. He has presented ES research and methods at several conferences in the United States, and internationally. Lipke has received several awards, including: PMI Eric Jenett Award, Earned Value Management Europe Award, and College of Performance Management Driessnack Award. As well, the Australian PGC Symposium has honored Mr. Lipke by naming their annual award the Walt Lipke Project Governance and Control Excellence Award.