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 reason to increase attention to managing schedule performance and improving planning.

Although 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. The tasks to the left of the vertical ES time-line, not completely darkened, are those possibly experiencing impediments and constraints (I/C), or poor process discipline. The darkened tasks to the right of the ES line indicate performance resulting from voids identified by the I/C tasks. Frequently, those darkened tasks to the right are executed without complete information. The performers of these tasks must necessarily anticipate the inputs expected from the incomplete preceding tasks; this consumes time and effort and has no associated earned value. Because the anticipated inputs are very likely misrepresentations of the future reality, the work accomplished (EV accrued) for these tasks usually contains significant amounts of rework. Complicating the problem, the rework created for a specific task will not be recognized for a period of time. The eventual rework will not be apparent until all of the inputs to the task are known or its output is recognized to be incompatible with the requirements of a subsequent task.



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How to cite this paper: Lipke, W. (2020). Project Duration Increase from Rework; PM World Journal, Vol. IX, Issue IV, April. Available online at https://pmworldlibrary.net/wp-content/uploads/2020/03/pmwj92-Apr2020-Lipke-Project-Duration-Increase-from-Rework.pdf



About the Author

Walt Lipke

Oklahoma, USA




Walt Lipke retired in 2005 as deputy chief of the Software Division at Tinker Air Force Base in the United States, where he led the organization to the 1999 SEI/IEEE award for Software Process Achievement. He is the creator of the Earned Schedule technique, which extracts schedule information from earned value data.

Credentials & Honors:

  • Master of Science Physics
  • Licensed Professional Engineer
  • Graduate of DOD Program Management Course
  • Physics honor society – Sigma Pi Sigma (SPS)
  • Academic honors – Phi Kappa Phi (FKF)
  • PMI Metrics SIG Scholar Award (2007)
  • PMI Eric Jenett Award (2007)
  • EVM Europe Award (2013)
  • CPM Driessnack Award (2014)
  • Australian Project Governance and Control Symposium established the annual Walt Lipke Project Governance and Control Excellence Award (2017)
  • Albert Nelson Marquis Lifetime Achievement Award (2018)

To view other works by Walt Lipke, visit his author showcase in the PM World Library at https://pmworldlibrary.net/authors/walt-lipke/