Earned schedule: Difference between revisions
Garrybooker (talk | contribs) Added citation to new book on the subject |
|||
| Line 1: | Line 1: | ||
'''Earned schedule (ES)''' is an extension to the theory and practice of [[earned value management]] (EVM). As of 2005, Earned Schedule is designated as an "emerging practice" by the [[Project Management Institute]]. It was introduced in 2003 a seminal article "Schedule is Different" by Walter Lipke, in ''The Measurable News'', the quarterly magazine of the College of Performance Management, of the [[Project Management Institute]]. |
'''Earned schedule (ES)''' is an extension to the theory and practice of [[earned value management]] (EVM). As of 2005, Earned Schedule is designated as an "emerging practice" by the [[Project Management Institute]]. It was introduced in 2003 a seminal article "Schedule is Different" by Walter Lipke, in ''The Measurable News'', the quarterly magazine of the College of Performance Management, of the [[Project Management Institute]]. The most thorough treatment of the subject can be found in the book ''Earned Schedule'', by Walter Lipke. <ref>{{cite book |
||
| last = Lipke |
|||
| first = Walter H. |
|||
| title = Earned Schedule |
|||
| publisher = Lulu Publishing |
|||
| date = 2009 |
|||
| pages = |
|||
| isbn = 978-0-557-17738-7 }} |
|||
</ref> |
|||
Traditionally, EVM tracks schedule variances ''not'' in units of time, but in units of currency (e.g. dollars) or quantity (e.g. labor hours). Of course, it is more natural to speak of schedule performance in units of time, but the problems with traditional schedule performance metrics are even deeper. Near the end of a project -- when schedule performance is often a primary concern -- the usefulness of traditional schedule metrics is demonstrably poor. In traditional EVM, a schedule variance (SV) of 0 or a schedule performance index (SPI) of 1 indicates that a project is exactly on schedule. However, when a project is completed, its SV is always 0 and SPI is always 1, even if the project was delivered unacceptably late. Similarly, a project can languish near completion (e.g. SPI = 0.95) and never be flagged as outside acceptable numerical tolerance. (Using traditional SV as an exception threshold, it is not uncommon that an SPI > 0.9 is considered acceptable.) |
Traditionally, EVM tracks schedule variances ''not'' in units of time, but in units of currency (e.g. dollars) or quantity (e.g. labor hours). Of course, it is more natural to speak of schedule performance in units of time, but the problems with traditional schedule performance metrics are even deeper. Near the end of a project -- when schedule performance is often a primary concern -- the usefulness of traditional schedule metrics is demonstrably poor. In traditional EVM, a schedule variance (SV) of 0 or a schedule performance index (SPI) of 1 indicates that a project is exactly on schedule. However, when a project is completed, its SV is always 0 and SPI is always 1, even if the project was delivered unacceptably late. Similarly, a project can languish near completion (e.g. SPI = 0.95) and never be flagged as outside acceptable numerical tolerance. (Using traditional SV as an exception threshold, it is not uncommon that an SPI > 0.9 is considered acceptable.) |
||
| Line 6: | Line 14: | ||
It has been stated that Earned Schedule provides a useful link between traditional Earned Value Analysis and traditional project schedule analysis -- a link that some say has been missing in traditional EVM theory. |
It has been stated that Earned Schedule provides a useful link between traditional Earned Value Analysis and traditional project schedule analysis -- a link that some say has been missing in traditional EVM theory. |
||
==Notes and References== |
|||
<references /> |
|||
==External links== |
==External links== |
||
Revision as of 23:31, 20 January 2010
Earned schedule (ES) is an extension to the theory and practice of earned value management (EVM). As of 2005, Earned Schedule is designated as an "emerging practice" by the Project Management Institute. It was introduced in 2003 a seminal article "Schedule is Different" by Walter Lipke, in The Measurable News, the quarterly magazine of the College of Performance Management, of the Project Management Institute. The most thorough treatment of the subject can be found in the book Earned Schedule, by Walter Lipke. [1]
Traditionally, EVM tracks schedule variances not in units of time, but in units of currency (e.g. dollars) or quantity (e.g. labor hours). Of course, it is more natural to speak of schedule performance in units of time, but the problems with traditional schedule performance metrics are even deeper. Near the end of a project -- when schedule performance is often a primary concern -- the usefulness of traditional schedule metrics is demonstrably poor. In traditional EVM, a schedule variance (SV) of 0 or a schedule performance index (SPI) of 1 indicates that a project is exactly on schedule. However, when a project is completed, its SV is always 0 and SPI is always 1, even if the project was delivered unacceptably late. Similarly, a project can languish near completion (e.g. SPI = 0.95) and never be flagged as outside acceptable numerical tolerance. (Using traditional SV as an exception threshold, it is not uncommon that an SPI > 0.9 is considered acceptable.)
To correct these problems, Earned Schedule theory renames the two traditional measures SV and SPI as SV($) and SPI($), to indicate clearly they are in units of currency or quantity, not time. Then, time-based quantities SV(t) and SPI(t) are created. A stated advantage of Earned Schedule methods is that no new data collection processes are required to implement and test Earned Schedule; it only requires updated formulas. Earned Schedule theory also provides updated formulas for predicting project completion date, using the time-based measures.
It has been stated that Earned Schedule provides a useful link between traditional Earned Value Analysis and traditional project schedule analysis -- a link that some say has been missing in traditional EVM theory.
Notes and References
- ^ Lipke, Walter H. (2009). Earned Schedule. Lulu Publishing. ISBN 978-0-557-17738-7.