# An Arrow on Arrow Diagram

An Arrow on Arrow (AON) diagram is developed to establish the sequence of the project activities, as shown in Fig. 4-1. Table 4-1 contains data that has been processed to perform a Project Evaluation Review Technique (PERT). The estimated time (Te) for completing the activity has been determined. Fig. 4-2 represents a PDM diagram based on the estimated times (Te). One critical path is identified as A-E-G-L-M for an estimated duration of 52.2 days. Non-critical activities are assessed for the probability of becoming critical. The paths that present a low risk are: ADHJNO (0.07 %), BDHJPQ (0.31%) and AEGQ (0%).   The paths that present a moderate risk of becoming critical are BDHKQ (3.07%) and AEIKQ (3.74%).

The path that presents a high risk of becoming critical is ACFIKQ at 43.25%. The certainty date (Tx) for 90% completion is determined with the central limit theorem and equates to 58.38 days. The expected duration (Tx) to give a 100% probability of completing the project is 70.2 days. Therefore a contingency of 18 days is required to ensure timely delivery of the project which equates to a 34% contingency level. Q.5 The planned budget for the project over the full duration is shown in Table 5-1.

An analysis of the Planned Value (PV), Earned Value (EV) and Actual Cost (AC) for week 10, 15 and 20 is performed. According to Tables 5-3 and 5-4, the project is over-budget by 37% and behind schedule by 28.4% at week 20. The figures suggest the project started at a slow pace but improved significantly over the 10-week period.   An estimate of completion is determined using the Remaining Budget method and based on the following formula: EAC=ACc+(BAC-EVc).   Substituting knows values: EAC = € 106,500 + (€ 228,000 - € 77,333) = € 29,167Therefore the project is estimated to be completed under budget by € 29,167.

A number of performance monitoring techniques have been employed to analyze the current status of the project. The techniques include the Quad Plot IV (Fig. 5-3), Critical Ratio Control Chart (Fig. 5-1) and Earned Value Chart (Fig. 5-2). Each graphical representation clearly illustrates that the project is underperforming and urgently requires intervention at the managerial level.

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