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al. (2019) replicated Christensen’s (1996) study using modern defense contracts and discovered similarities and differences in their stability results. Kim et al. (2019) found EAC CPI achieves stability within 10% deviation from cost at completion at 55% complete, which is comparable to Christensen’s (1996) findings of 50% complete. However, and inconsistent with Christensen’s findings, Kim et al. (2019) found EAC SCI achieves stability within 10% deviation from cost at completion at 50% complete, closely mirroring EAC CPI . Notably, and for this article’s focus, neither Christensen (1996) nor Kim et al. (2019) examined the length of the development period as a possible discriminator in their results.
Even when a project was over schedule, EVM schedule indicators depict on-target schedule performance at project completion. Another issue with conventional EVM schedule indicators is their expression of schedule in measures of value (i.e., cost) instead of measures of time.
The EVM studies discussed to this point are all focused on cost performance, rather than schedule. Although EVM is used extensively in program management, Lipke (2003) addressed an intrinsic pitfall in its depiction of schedule performance. The issue lies in EVM’s schedule indicators being a function of both the BCWP and BCWS. Due to the Budget at Completion (BAC) end point of these two elements, a divergence in the current trends of schedule indicators can be observed as the earned value converges to the planned value at project completion. Thus, even when a project was over schedule, EVM schedule indicators depict on-target schedule performance at project completion. Another issue with conventional EVM schedule indicators is their expression of schedule in measures of value (i.e., cost) instead of measures of time. This provides program managers with often misleading indications of schedule performance (Corovic, 2006). Lipke (2003) remedies these issues with EVM schedule indicators by introducing the concept of Earned Schedule (ES). This technique provides time-based schedule indicators that have shown convergence to the actual results at project completion analogous to cost indicators (Crumrine et al., 2014; Henderson & Zwikael, 2008; Lipke, 2015; Petter et al., 2015).
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Defense ARJ , Spring 2025, Vol. 32 No. 1
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