Earned Schedule


The First 20 Years



By Patrick Weaver

Melbourne, Australia


The concept of Earned Schedule (ES) was introduced to the Earned Value Management (EVM) community in March 2003, when Walt Lipke published Schedule is Different[1] in the College of Performance Management (CPM) Measurable News.

Earned Schedule is an extension to the EVM system that provides an enhanced ability to predict project completion dates, and is the bridge for performing meaningful schedule analysis from EVM data. It uses the same data as traditional EVM, but shifts the calculations from the cost axis to the time axis.

Despite early controversies over the approach, studies by a range of universities and other authorities have shown the project duration predictions calculated by ES are as accurate as the cost predictions generated by traditional EVM. Twenty years after its creation, ES is now seen as a standard component of EVM and is included in most published Standards including ISO and ANSI/PMI.


Before tracing the development of Earned Schedule and its contribution to the discipline of project management, it is important to precisely define what is meant by Earned Schedule and Earned Value Management in the context of this paper.

Earned Schedule (ES)

As outlined above, Earned Schedule is an extension of Earned Value Management, it is defined in ISO 21508:2018 Earned value management in project and programme management, and ANSI/PMI 19-006-2019 The Standard for Earned Value Management.

The primary function of ES is to predict the project completion date based on the value of work planned to be completed (PV) and actual value of work accomplished (EV) in a particular period, or as at a nominated date, using data contained in the project’s EVM system. It extends the capabilities of traditional EVM by calculating schedule metrics and indicators on the time axis, including SPI(t) and SV(t) as well as the predicted project completion date. Consequently, the prerequisites needed to implement ES are a project, running an EVM system (EVMS) as part of the overall project controls framework.

Note: ES is derived from and forms part of an EVMS. It has no connection to any other time management and/or time payment, and/or incentive payment system, as used in various factories, mills and projects. These time management/payment systems have a long history and many are still in use today, but it is important to note that ES is not a time recording, time management or payment system.

Earned Value Management (EVM)

The concepts of Earned Value Management, and an Earned Value Management System (EVMS) used in this paper are based on the two standards detailed above, plus NDIA/EIA 748-D, Earned Value Management Systems (EVMS). While the management focus, acronyms and some details vary between these three standards, they are consistent in their approach to defining what EVM is, and what it is not.

The standards define EVM as a project performance management system. The basic requirement needed to establish an EVMS is an identified project, in which the responsibilities of each manager is defined by reference to a Work Breakdown Structure (WBS)[2]. Then the EVMS creates measures of performance at the Work Package and Control Account levels and rolls this information up to the overall project level.

The core drivers of an EVMS are the value of work planned to be accomplished (PV), the value of the work actually completed (EV), and the actual costs incurred in accomplishing that work (AC); either in a reporting period, or cumulative to the date of the assessment. The value metric most commonly used in an EVMS is money, but any measure of value that is uniform across the project can be used (eg, work hours).

An EVMS as defined in the standards is not a cost engineering system, a financial controls system, or a payment/contract management system. These other systems form an important part of a well-managed project’s overall controls system, but their inputs to the EVMS are limited.


To read entire paper, click here

How to cite this paper: Weaver, P. (2023). Earned Schedule – the First 20 Years; PM World Journal, Vol. XII, Issue III, March. Available online at https://pmworldjournal.com/wp-content/uploads/2023/03/pmwj127-Mar2023-Weaver-Earned-schedule-the-first-20-years.pdf

About the Author

Patrick Weaver              

Melbourne, Australia


 Patrick Weaver, PMP, PMI-SP, FAICD, FCIOB, is the Managing Director of Mosaic Project Services Pty Ltd, an Australian project management consultancy specializing in project control systems.  He is a Fellow of the Chartered Institute of Building, Australasia (FCIOB) and a Fellow of the Australian Institute of Company Directors (FAICD). He is a member of the PMI Melbourne Chapter (Australia), as well a full member of AIPM, and the Project Management College of Scheduling (PMCOS).

Patrick has over 50 years’ experience in Project Management. His career was initially focused on the planning and managing of construction, engineering and infrastructure projects in the UK and Australia. The last 35 years has seen his businesses and experience expand to include the successful delivery of project scheduling services and PMOs in a range of government, ICT and business environments; with a strong focus on project management training.

His consultancy work encompasses: developing and advising on project schedules, developing and presenting PM training courses, managing the development of internal project control systems for client organizations, and assisting with dispute resolution and claims management.

In the last few years, Patrick has sought to ‘give back’ to the industry he has participated in since leaving college through contributions to the development of the project management profession. In addition to his committee roles, he has presented papers at a wide range of project management conferences in the USA, Europe, Asia and Australia, has an on-going role with the PGCS conference in Australia and is part of the Australian delegation to ISO TC258.

Patrick can be contacted at patw@mosaicprojects.com.au or at www.mosaicprojects.com.au.

To view other works by Pat Weaver, visit his author showcase in the PM World Library.net at https://pmworldlibrary.net/authors/patrick-weaver/ or visit his website.

[1] Lipke, Walt. Schedule is Different.  The Measurable News, March & Summer 2003. Download from: https://mosaicprojects.com.au/PDF-Gen/Schedule_is_different.pdf

[2] The concept of a formal WBS structure emerges as part of the PERT, and PERT/COST, developments in the late 1950s and 60s. For more on the history of WBS see: https://mosaicprojects.com.au/PMKI-ZSY-020.php#WBS