Schedule Adherence and Rework



By Walt Lipke

Oklahoma, USA




When project performance is such that the product is delivered with expected functionality at the time and price agreed between the customer and supplier, it is deemed “successful.” The rework, encumbering any project, has a measurable impact on whether a project can achieve success. The project manager, who exercises control of the contributors to rework, can greatly enhance the prospect of delivering the product within its constraints. A significant portion of rework is caused by deviating from the project plan and its associated schedule. The measure of schedule adherence is derived from applying Earned Schedule to Earned Value Management data. This paper first reviews the concept of schedule adherence and then develops an approach to understanding the cost impact from not adhering to the schedule. Finally, an index is proposed which provides information to assist project control and to forecast the cost associated with imperfect schedule adherence.   


An extension to Earned Value Management (EVM), Earned Schedule (ES), was introduced in the March 2003 issue of The Measurable News [Lipke, 2003]. The purpose of ES was to overcome the anomalous behavior of the EVM schedule performance indicators by providing reliable time-based indicators.[1] After ES was initially verified [Henderson, 2003] it was, subsequently, applied to forecasting project duration [Henderson, 2004]. Since that time has ES propagated globally and is now a generally accepted practice with its recent inclusion in the 2nd edition of the PMI Practice Standard for Earned Value Management [PMI, 2011].[2]

One unique quality of the ES measure is that it facilitates identifying the specific planned value (PV) which should have been accomplished for the reported earned value (EV). This characteristic was first explained and examined in the article, “Connecting Earned Value to the Schedule,” published in the Winter 2004 issue of The Measurable News [Lipke, 2004].  Subsequently, this extended capability of ES was more fully elaborated in the April, 2008 CrossTalk article, “Schedule Adherence: a useful measure for project management” [Lipke, 2008].  

Because the task specific PV is identifiable, comparisons can be made to the task EV reported. The differences in PV and EV for each task are utilized to isolate problems occurring in the execution of the project. When the difference, EV – PV, is negative, there is a possibility of a constraint or impediment preventing task progress. This information is extremely useful. Having these tasks identified, allows the project manager to focus on investigating and relieving problems that are causing workarounds. Minimizing the impact of constraints and impediments, in turn, minimizes the extent of workarounds, thus maximizing execution in agreement with the schedule. The more execution agreement there is between actual accomplishment and the schedule, the greater the performance efficiency becomes – for both cost and schedule.

Along with the negative differences previously discussed, there are positive differences identified for specific tasks. The positive differences expose areas where rework may occur. There are many causes of rework:

  • poor planning stemming from requirements misinterpretation, incorrect task sequencing, and poor estimation
  • defective work
  • poor requirements management
  • schedule compression during execution
  • overzealous quality assurance

However, the rework identified when EV – PV is positive is none of the ones cited above. The rework for which we are concerned is solely caused by project execution not in the activity sequence prescribed by the schedule. Although out of sequence performance is only one of the six contributors to rework mentioned, it has a major impact. Out of sequence performance is pervasive in that it is not aligned with a single aspect or project event. Rather, it occurs dynamically and can involve any, and possibly all of the project team throughout the entire period of performance.

For readers who have some background in quality and process improvement activity, the discussion thus far may bring to mind the idea of process discipline. The lack of process discipline leads to the creation of defects and inefficient performance. As has been described thus far, ES provides a way to identify and measure process performance discipline.


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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 published in PM World Today on-line journal (July 2011). The article is no longer accessible as the journal ceased publication with its last issue in March 2012. The article has been published, as well, in The Measurable News (2011, Issue 1), and CrossTalk (2012, Vol 25, No. 6, on-line).  It is republished here with the author’s permission.

How to cite this paper: Lipke, W. (2019). Schedule Adherence and Rework; originally published in PM World Today (July 2011) and in The Measurable News (2011, Issue 1), and CrossTalk (2012, Vol 25, No. 6, on-line); PM World Journal, Vol. VIII, Issue VI, July.  Available online at https://pmworldlibrary.net/wp-content/uploads/2019/07/pmwj83-Jul2019-Lipke-Schedule-Adherence-and-Rework.pdf



About the Author

Walt Lipke

Oklahoma City, USA




Walt Lipke retired in 2005 as deputy chief of the Software Division at Tinker Air Force Base, 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)
  • Who’s Who in the World (2010)
  • 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/


[1] The schedule performance indicators derived from Earned Schedule are Schedule Variance-time (SV(t) = ES – AT) and Schedule Performance Index-time (SPI(t) = ES / AT), where AT is the time duration at which an EV measurement is reported.




[2] Since the initial publication of this paper, ES has been recognized and included in the PMI Project Management Body of Knowledge, 6th Ed. (2017), PMI Practice Standard for Scheduling, 3rd Ed. (2019), and the ISO 21508:2018: Earned value management in project and programme management.