Quản trị kinh doanh - Chapter 6: Estimating project, times and costs

CHAPTER 6 Estimating Project, Times and CostsLearning Elements6.1 Understand that estimating can be carried out to differing levels of detail and accuracy. 6.2 Apply any number of estimating techniques to assist in scoping and planning a project. 6.3 Understand the concept of contingency versus padding. RECAP. Leading on from Step 4. Estimating: Moving towards a draft budget and scheduleThe journey from WBS to estimating and the creation of the budget schedule and resource matrixESTIMATINGEstimates are needed to:Support good decisionsDetermine whether the project is worth doingDetermine how long the project should take and its overall costSchedule workDetermine the resource required (human and other)Develop time-phased budgets (cash flow)Establish the project baselineDetermine how well the project is progressing What is being estimated?ResourcesDurationsCostsEstimating Guidelines for Time, Costs and Resources Consider:ResponsibilityUse several people to estimateNormal conditionsTime unitsIndependenceContingenciesCarrying out a risk assessmentCost of Quality (CoQ)Top-down versus Bottom-up EstimatingTop-down approach Are usually derived from someone who uses experience and/or information to determine the project duration and total cost.Bottom-up approach Can serve as a check on cost elements in the WBS by rolling up the work packages and associated cost accounts to major deliverables at the work package level.Hybrid – phase estimatingUsed when an unusual amount of uncertainty surrounds a project and it is impractical to estimate times and costs for the entire project. Methods for Estimating Project Costs, Time and ResourcesConsensus methodsExpert judgmentAlternative analysisParametric estimatingAnalogous method3-point estimateMethods for Estimating Project Costs, Time and Resources(cont.)Vendor bid analysisEstimating tools and systemsFunction point methodsLearning curvesTemplate methodsRange estimating Analogous Estimating ‘Analogous estimating is a technique for estimating the duration or cost of an activity or a project using historical data from a similar activity or project. ‘Analogous estimating uses parameters from a previous, similar project, such as duration, budget, size, weight, and complexity, as the basis for estimating the same parameter or measure for a future project.’ (PMI 2013, p. 169)  Parametric Estimating ‘Parametric estimating is an estimating technique in which an algorithm is used to calculate cost or duration based on historical data and project parameters. ‘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’. (PMI 2013, p. 170)Three-point EstimateOptimistic + (4 x Most Likely) + Pessimistic6Also known as the PERT method.Summary of Estimating Tools Level of Detail in EstimatingThe estimating trumpetRefining EstimatesReasons for adjusting estimatesInteraction costs are hidden in estimates.Normal conditions do not apply.Things go wrong on projects.Changes in project scope and plans.Adjusting estimatesTime and cost estimates of specific activities are adjusted as the risks, resources and situation particulars become more clearly defined.Key Terms3-point estimatebottom-up estimatescontingencyCost of Quality (CoQ)Delphi Methoddirect costsestimating toolsfunction pointsindirect costs (G&A or overhead costs)learning curvepadding estimatesPERT methodphase estimatingrange estimatingtemplatestop-down estimates