https://www.dau.edu
FIGURE 2. GRAPHICAL COMPARISON OF PERCENT DEVIATIONS FROM COST AT COMPLETION FOR EAC’S CALCULATED WITH ES METRICS
EAC Comparison (Earned Schedule)
5%
0%
-5%
-10%
-15%
EACspi(t) EACsci(t)
-20%
-25%
-30%
-35%
-40% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Project Completion
Note. DCAC = Deviation from Cost at Completion; EAC = Estimate at Completion; ES = Earned Schedule; sci = Schedule Cost Index; spi = Schedule Performance Index.
TABLE 2. SUMMARY OF PREVIOUS LITERATURE STABILITY RESULTS AT 10% DEVIATION FROM COST AT COMPLETION Author(s) Contracts Analyzed Metric
Percent Complete
Christensen
Development
CPI
60
Christensen
Development
SPI($)
60
Christensen
Development
SCI($)*
20
Christensen
Dev & Prod
CPI
50
Christensen
Dev & Prod
SPI($)
0
Christensen
Dev & Prod
SCI($)
0
Kim et al.
Dev & Prod
CPI
55
Kim et al.
Dev & Prod
SCI($)
50
*Oft-Cited “Stability Rule” Note. CPI = Cost Performance Index; Dev = Development; Prod = Production; SCI = Schedule Cost Index; SPI = Schedule Performance Index. These results from Christensen (1996) and Kim et al. (2019) describe the accuracy of EACs generally amongst both development and production contracts. For development contracts, Christensen (1996) found EAC CPI and EAC SPI ($) to achieve stability within 10% deviation at approximately
65
Defense ARJ , Spring 2025, Vol. 32 No. 1
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