‘Completion in time’ is a crucial element of project management. Previous studies show that earned value management (EVM), earned schedule method, or earned duration management do not give an accurate project completion time estimation (PCTE) because of theoretical weaknesses. Inaccurate PCTE may provide misleading information, so that the project manager cannot take effective schedule control actions timely, and thus it results in failure of project time management. To improve the above-mentioned problem, this research proposes a quantity-based project duration estimating method (Q-PDEM), which calculates the PCTE using the de facto work quantities and the updated productivity information of activities. The results of two case studies show that the proposed Q-PDEM gives a 7.55% better mean absolute percentage error (MAPE) than the existing methods for predicted project completion duration for Case I, and 24.54% for Case II. It is concluded that the proposed Q-PDEM gives a more accurate estimation of the time for project completion and allows more effective control of the project schedule.

“及时完成”是项目管理的关键要素。先前的研究表明，由于理论上的缺陷，挣值管理（EVM），挣进度表方法或挣工期管理无法给出准确的项目完成时间估算（PCTE）。不准确的PCTE可能会提供误导性的信息，从而使项目经理无法及时采取有效的进度控制措施，从而导致项目时间管理失败。为了解决上述问题，本研究提出了一种基于数量的项目工期估算方法（Q-PDEM），该方法使用实际的方法计算PCTE。工作量和活动的更新生产率信息。两项案例研究的结果表明，对于案例I而言，拟议的Q-PDEM预测项目完成时间比现有方法的平均绝对百分比误差（MAPE）高7.55％，对于案例II则提高了24.54％。结论是，提出的Q-PDEM可以更准确地估计项目完成的时间，并可以更有效地控制项目进度。