多重要徑之下專案完工機率之研究

Probability for Project Complete with Multiplex Critical Path

張寬寬(Kuan-Kuan Chang)

指導教授 ： 林逾先

國立臺北科技大學/管理學院/商業自動化與管理研究所/碩士(2009年)

摘要

專案具有相當複雜性，且執行時間並非固定，通常專案作業時間為一隨機變數，專案的完成時間亦必為一隨機變數，所有隨機性專案問題中，首要先解決之問題為專案完工時間之估算，而需要的完工時程又充滿著不確定性。對於管理者而言，讓專案在限期內完工，是一重要課題。
要徑法（CPM）工期是採單時估算的方式，並無不確定性工期之考慮。計畫評核術（PERT）則以平均最長路徑，來估計需要時程要徑，但忽略網路中其他路徑對於總工期之影響。若是網路中包含了兩條或數條相近之要徑天數路徑，則PERT就無法確切預估某信心水準下完工之天數與平均完工天數。且當兩路徑之完成時間機率分配值域相接近或其變異量較大的話，則PERT估計的偏差會愈明顯。本研究建構一個網路模型，利用三種不用方法來比較各別的完工機率，並假設作業在不同的峰態，觀察其完工機率的變化趨勢。

關鍵字

多重要徑 ； 計畫評核術 ； 或然率網圖評核術

並列摘要

Projects are often quite complex with a lot of uncertainties on both project activity time and project completion time. Project activity time can be viewed as a random variable whereby the project completion also becomes a random variable. For a project manager, it is important to ensure project completion within the due time.
CPM (Critical Path Method) uses single-time estimation which does not consider time variability. On the other hand, PERT (Program Evaluation and Review Technique) normally estimates of project duration based on the critical path and ignores the influence of other paths. For a project network with two or more critical paths with similar lengths, PERT will not be able to give accurate estimates of the mean duration and the duration for a given confidence level. When the probability distributions for the time of two paths are close or have large variances, the deviation of the PERT estimate becomes evident.
This research construct a network model and compare the probability of project completion time using three different approaches. It also observes the tendency of change under different probability distribution.

並列關鍵字

Multiplex Critical Path ； PERT ； PNET

參考文獻

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