Within earned value management, the cost performance index (CPI) and the critical ratio (CR) are used to generate the estimates at completion (EACs). According to the research in the 1990s, estimating the final contract’s cost at completion (CAC) using EACCR is a quicker predictor of the actual final cost versus using EACCPI. This paper aims to investigate whether this trend stills holds for modern department of defense contracts.,Accessing the Cost Assessment Data Enterprise (CADE) database, 451 contracts consisting of 863 contract line item numbers (CLINs) were initially retrieved and analyzed in three stages. The first replicated the work conducted in 1990s. The second stage entailed calculating 95 per cent confidence intervals and hypothesis tests regarding percentage accuracy of EACs for a contract’s final CAC. Lastly, regression analysis was conducted to characterize major, moderate and minor influencers on EAC reliability.,For modern contracts, EACCR aligns more with EACCPI and no longer demonstrates early accuracy of a contract’s final CAC. Contract percentage completion strongly reduced the per cent error of estimating CAC, while cost-plus-fixed-fee contracts and those with no work breakdown structure greater than Level 2 negatively affected accuracy.,To militate against optimism of early assessment of a contract's true cost.,This paper provides empirical evidence that EACCR behaves more like EACCPI with respect to modern contracts, suggesting that today’s contracts have relatively high SPI. Therefore, caution is warranted for program managers when estimating the CAC from contract initiation up to and slightly beyond the mid-point of completion.

中文翻译：

---

再谈国防部合同完成时估计的可靠性

在挣值管理中，成本绩效指数（CPI）和关键比率（CR）用于生成完成时的估计（EAC）。根据1990年代的研究，与使用EACCPI相比，使用EACCR估算最终合同的完成成本（CAC）是实际最终成本的更快预测指标。本文旨在研究这种趋势是否仍然适用于现代国防部合同。通过访问成本评估数据企业（CADE）数据库，分三个阶段初步检索和分析了由863合同项目编号（CLIN）组成的451合同。第一次复制了1990年代进行的工作。第二阶段需要计算95％的置信区间，并进行关于合同最终CAC的EAC的百分比准确性的假设检验。最后，进行了回归分析以表征EAC可靠性的主要影响因素，中等影响因素和次要影响因素。对于现代合同，EACCR与EACCPI更加吻合，并且不再证明合同最终CAC的早期准确性。合同完成百分比大大降低了估算CAC的百分比误差，而成本加固定费用合同以及那些没有工作分解结构大于2级的合同对准确性造成了负面影响。为了避免对早期评估合同真实成本的乐观情绪本文提供的经验证据表明，EACCR在现代合同方面表现得更像EACCPI，这表明当今的合同具有相对较高的SPI。因此，在估算从合同启动到完成点甚至稍稍超过完成点的CAC时，项目经理应谨慎行事。