Chapter 9-Cost Estimating

摘要

Cost estimating is of integral importance to the quality of the cost and scheduling program on any project. Of paramount importanceto the success of a project is the integrity of the cost estimate; and this is ensured by the use of the appropriate cost estimatingmethodology. The cost estimate becomes the basis for setting up the cost budget, resources and the ensuing progress and schedulemonitoring processes during project execution. To achieve this, a cost estimating basis/framework is necessary.The cost estimating framework that is developed in this chapter includes:1. A system for the classification of cost estimating.2. The methodologies used in the preparation of cost estimates.3. Establishing estimating accuracy as it relates to the scope definition.4. The application of risk analysis to contingency.This chapter presents functional examples for the different cost estimating methodologies inclusive of:1. Conceptual Estimating2. Ratio or Factored Estimating3. Parametric Estimating4. Detailed or Deterministic EstimatingThis cost estimating chapter also establishes the relevance of the Work Breakdown Structure (WBS) and Resource BreakdownStructure (RBS) to the structure of the estimate and the ensuing budget and schedule. Finally, good estimating practices are stressedsuch as; the inclusion of the Basis of the Estimate (BOE) document as a pre-requisite in presenting the final estimate.In conclusion, this chapter provides a solid background in estimating, and establishes that estimates are a vital component to projectsuccess to establish project budgets and to provide accurate information to support scheduling, cost monitoring, and progressmeasurement of a project during execution.