“One of the notable features around ES has been the amount of hostility towards the concept generated by traditional Earned Value advocates” Pat Weaver

“The technique has largely been championed by Walt Lipke in the US and Kym Henderson in Australia. Prophets in their own lands are often damned and this was no exception.” APM’s Earned Value SIG

The above and similar strong opinions are part of a debate between project managers over the past 11 years on the use of the Earned Schedule (ES) predictor as an extension of the traditional Earned Value Management (EMV) tool.  EMV has been in use since the 1960s as a program management tool, giving good predictions early in the project of final project costs. In a 2003 paper, Schedule is Different Walt Lipke introducing the concept of Earned Schedule (ES) to give good estimates of project completion dates. ES was not warmly received in the US but attracted early support from Australia in Kym Henderson’s paper  “Earned Schedule: A Breakthrough Extension to Earned Value Theory?, A Retrospective Analysis of Real Project Data,” in The Measurable News, Summer 2003.

Kym’ s findings were that “the ES concept has validity….By extending EVM to include valid duration based schedule performance , ES may be considered a “breakthrough” extension to Earned Value theory” , see http://www.earnedschedule.com/Docs/Earned%20Schedule%20-%20A%20Breakthrough%20Extension%20to%20EVM.pdf.

This suggestion fell on deaf ears in the US but ES gradually gained support elsewhere. A Stephan Vandevoorde and  Mario Vanhoucke paper “A Comparison of Different Project Forecasting Methods Using Earned Value Metrics,” was published in the International Journal of Project Management, May 2006, with the finding that “The three real-life projects reveal that the earned schedule method was the only method which showed satisfying and reliable results during the whole project duration. “  However, this finding was obscured by  other technical discussion, see


Support from Quebec was more forthright.  A paper by Radenko Corovic stated , “Schedule performance indicators calculated with conventional EVM are deficient for the majority of commercial projects and, as such, they shouldn’t be used in schedule performance management. They are not just less precise, they are fundamentally wrong. On the other hand, the alternative practice called Earned Schedule works very well…. In my opinion, there is no doubt that the EVM rules and standards related to schedule performance should be changed and established according to the proposed Earned Schedule approach. ”

See  “Why EVM Is Not Good for Schedule Performance Analyses (and how it could be…),” in The Measurable News, Winter 2006-2007,


By 2010 ES had still to be accepted and a white paper by the APM’s Earned Value SIG, EARNED SCHEDULE  An emerging Earned Value technique , noted “The technique has largely been championed by Walt Lipke in the US and Kym Henderson in Australia. Prophets in their own lands are often damned and this was no exception. The UK offered a non-judgmental platform and interest has slowly but surely grown”, see http://www.apm.org.uk/sites/default/files/20100302%20EVM%20WP%200110.pdf.

An interesting comment on the APM blog , by patw on 19 June, 2010, notes ”The root cause of much of the furore around ES is derived from the studies undertaken to determine the validity of the model and ‘prove’ ES was as reliable in predicting time outcomes as the EAC calculations were in predicting cost outcomes.  The result of several significant studies has been to confirm ES is as accurate as EAC in predicting project completion data.  However, the ES studies also clearly demonstrated the generalisation of the ‘20% stability rule’ has been inappropriate.  The 20% stability rule simply does not apply to most projects…. The ES debate/controversy has largely been promulgated by people wishing to protect the ‘20% rule’ by denigrating ES”, see

http://www.apm.org.uk/content/earned-schedule-white-paper  (which summarises the “20% rule”.)

In 2013, 10 years after Walt Lipke’s paper, a Mosaicproject’s blog, April 22, 2013 by Pat Weaver notes  “One of the notable features around ES has been the amount of hostility towards the concept generated by traditional Earned Value advocates… One step towards eliminating this destructive debate was achieved this month – at last there is definitive research that validates ES as a technique”, see http://mosaicprojects.wordpress.com/2013/04/22/earned-schedule-comes-of-age/, The definitive research Pat referred to was a research thesis by Capt Kevin Crumrine, ‘A Comparison of Earned Value Management and Earned Schedule as Schedule Predictors on DoD ACAT I Programs’, see http://www.evmlibrary.org/library/Crumrine%20Final%20Thesis.pdf.

The latest news, from the crosstalkonline March/April 2014  issue, is a follow-on from Capt Crumrine’s  2013 research, which notes “This paper overcomes the previous literature shortcomings by analyzing over 64 contracts in major Air Force aircraft acquisition programs to determine whether ES provides more timely and accurate information. These contracts include software intensive contracts such as avionics along with hardware intensive contracts such as engines, capturing the full spectrum of an aircraft acquisition effort.” The approach and conclusions, summarised in the Abstract, are “This paper first analyzes whether ES and Earned Value Management (EVM) provide fundamentally different information for program managers. It then examines which technique, ES or EVM, provides more timely and accurate schedule predictors in a broad spectrum of military weapon system programs. We find ES to be more timely and accurate both in software intensive contracts and in the sample size as a whole.“ For the full paper, see Earned Schedule 10 Years Later Analyzing Military Programs http://www.crosstalkonline.org/storage/issue-archives/2014/201403/201403-Crumrine.pdf.

While the weight of scientific evidence now strongly favours ES, another aspect of the EMV and ES saga which has emerged over the past few years is an acrimonious debate on whether they can be used on Agile projects. However, that is a subject for a later Issue.