實獲工期管理(EDM(t))方法是著名的實獲值管理(EVM)方法的延伸，此方法的核心乃是以時間為基礎的衡量指標。EDM(t)通常用於專案狀態分析和預測專案的最終工期。一般預測的關鍵問題在於確保結果之準確性，因為不準確可能會提供誤導性訊息，從而可能導致錯誤的後續改正行動。然而，EDM(t)在處理對於要徑與非要徑作業下的專案總工期預測仍有不足，導致預測結果不正確。為解決此一問題，本研究提出EDM(t)+，透過將專案作業分為兩類型：要徑和非要徑，並據此建立相關計算公式，以提高預測準確性。本研究對原始EDM(t)和EDM(t)+方法進行專案不同屬性的預測結果，並採用平均絕對百分比誤差 (MAPE)指標，分析其準確性。由於MAPE提供估計值與實際結果差異的平均百分比，故MAPE越低表示預測越準確。經過一系列模擬和實際案例分析後，本研究發現所提出的EDM(t)+方法優於原始EDM(t)方法，進而確認EDM(t)+ 在準確預測專案工期方面更有效。雖然本研究目前的成果已經相當可信，但仍存在實務案例測試數量有限的不足，故建議後續研究可更廣泛地進行實務案例的額外驗證，以提升EDM(t)+方法的可靠性。;Earned Duration Management (EDM) approach is an extension of the well-known Earned Value Management (EVM) methodology, specifically focusing on time-based metrics. EDM is widely used for project status analysis and forecasting the project′s final duration. The critical concern in forecasting lies in ensuring accuracy, as inaccuracies can furnish misleading information, potentially leading to misguided corrective actions. However, EDM faces a challenge in determining the total project duration for critical and non-critical activities, potentially leading to incorrect results. This study proposed EDM(t)+, utilizing a modified formula, to enhance forecasting accuracy by categorizing project activities into critical and non-critical groups, and then compared the original EDM and the EDM(t)+ approach to prove its advantages. This comparison involves considering various characteristics of the project. The study employs a metric known as the mean absolute percentage error (MAPE) to measure forecasting accuracy. MAPE calculates the average percentage by which forecasts differ from actual results. A lower MAPE indicates more accurate forecasting. After conducting a series of simulations and real-world case studies, the proposed approach EDM(t)+ consistently outperforms the original EDM approach. This suggests that EDM(t)+ is more effective in forecasting project duration accurately. While the results are promising, the study acknowledges limitations in the number of real-world cases considered. Conducting additional validation across a broader range of practical projects to ensure the reliability of the EDM(t)+ method is suggested in the near future.
