Effective Measurement of Time Performance Using Earned Value Management (EVM)

A proposed modified version for SPI tested across various industries and project types

Neste artigo que mereceu o destaque da revista eletrónica internacional PM World Today do PM Forum, Alexandre Rodrigues propõe uma nova versão (i.e. fórmula) para o indicador de desempenho de prazo SPI (Schedule Performance Index) que corrige as limitações da versão original no modelo EVM. Este novo indicador – SPI modificado – é comparado com a alternativa SPI(time) que tem vindo a ser apresentada por alguns autores. Neste artigo, são apresentados vários exemplos comparativos.  Segundo comenta o perito Britânico Darren Dalcher, na sua crítica a este trabalho inovador: “The project management discipline is indebted to Dr. Rodrigues and his colleagues for continuing to challenge the boundaries of the discipline. Work in this area is concerned with addressing concerns observed in practice and the new ideas presented by Dr. Rodrigues have been applied successfully in empirical settings playing a key part in solving problems and improving our ability to measure performance and improve the track record of project delivery.”

Alexandre Rodrigues, International Correspondent - PM Forum, Outubro 2010

 Earned Value Management (EVM) is a project performance measurement technique, sometimes referred to as being primarily oriented towards cost management but with limited applicability to managing time performance. There have been various arguments supporting this perspective, namely: it ignores the detailed aspects of the schedule like floats and the critical path, its indicators are based on currency value hence not intuitive for time management, and finally the time performance indicator SPI always gives the value of 1 (i.e. a project “on time”) in late or early finishes. The last argument in particular is typically used to declare SPI as an invalid or unreliable time performance indicator. However, all of these arguments are only apparent. As we will demonstrate in this paper EVM can provide useful and valid time performance measures. The problem with the SPI indicator floating towards the value of 1 has been the subject of alternative approaches, for example its calculation based on the concept of Earned Schedule. While this alternative approach resolves the problem of SPI floating towards one in late or early finishes, the secondary effect is that it also gives this indicator a different meaning than the original concept. Based on academic research using computer simulation models, and on practical applications in real life projects, the author has developed an extended version of the original SPI (based on volume of work), which ensures the validity of this indicator throughout the whole execution period for the project. The solution found to overcome the weakness of the original SPI indicator preserves the original meaning of the time performance concept, i.e. how fast against the plan is the volume of work being accomplished. This extended modified version of SPI has been used in several projects across various industries, in different countries, and it has successfully delivered useful and valid performance information. The extended model developed includes additional formulae for various “to complete on time” indicators (TSPI) and “at completion” forecasts. This paper briefly explains the modified version of SPI and it also discusses the overall validity of using EVM to support effectively project time management. Some practical examples are also presented to illustrate the concepts. The use of SPI-based time performance indicators for the purpose of Risk Management under conditions of uncertainty is also discussed.

Para leitura completa deste artigo, poderá consular a nossa secção de arquivo aqui >>

ver outros artigos