36 64 estimate activity durations the process of

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Unformatted text preview: teractions. • Many additional interactions are possible. 36 6.4 Estimate Activity Durations • The process of approximating the number of work periods needed to complete individual activities with estimated resources. • The duration estimate is progressively elaborated, and the process considers the quality and availability of the input data. • Analogous estimating: uses parameters such as duration, budget, size, weight, and complexity, from a previous, similar project, as the basis for estimating the same parameter or measure for a future project. It is generally less accurate, but less costly and time consuming than other techniques. 37 6.4 Estimate Activity Durations (cont’d) • Parametric estimating: uses a statistical relationship between historical data and other variables (e.g., square footage in construction) to calculate an estimate for activity parameters, such as cost, budget, and duration. • Three-point estimates: a method originated from Program Evaluation and Review Technique (PERT) and considering estimation uncertainty and risk. PERT uses 3 estimates: – Most likely (tM): activity duration given the resources likely to be assigned, their productivity and availability – Optimistic (tO): activity duration of the best-case scenario – Pessimistic (tP): activity duration of the worst-case scenario – Expected (tE) = (tO + 4tE + tP) / 6 • Reserve analysis: includes contingency reserves into duration estimates for schedule uncertainty. The reserve may be a percentage of duration, a fixed time period, or developed using quantitative analysis methods. 38 6.5 Develop Schedule • The process of analyzing activity sequences, durations, resource requirements, and schedule constraints to create the project schedule. A schedule with milestones and planned start and finish dates is generated by entering the activities, durations, and resources into the scheduling tool. • Developing an acceptable project schedule is an iterative process. 39 6.5 Develop Schedule • Critical Path Method: calculates the theoretical early start and finish dates, and late start and finish dates, for all activities. • Critical...
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This document was uploaded on 01/28/2014.

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