ASTM E2516-2011 Standard Classification for Cost Estimate Classification System《成本估算分类系统的标准分类》.pdf

1、Designation: E2516 11Standard Classification forCost Estimate Classification System1, 2This standard is issued under the fixed designation E2516; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number i

2、n parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This classification provides a generic classification sys-tem for cost estimates and provides guidelines for applying theclassification to cost

3、 estimates.1.2 This classification maps the phases and stages of costestimating to a generic maturity and quality matrix, keyed to adegre of project definition, that can be applied across a widevariety of industries.1.3 The Cost Estimate Classification System has beendeveloped in a way that:1.3.1 pr

4、ovides a common understanding of the conceptsinvolved with classifying cost estimates;1.3.2 defines and correlates the major characteristics used inclassifying cost estimates, and;1.3.3 uses the degree of project definition as the primarycharacteristic used to categorize estimate classes.2. Referenc

5、ed Documents2.1 ASTM Standards:3E631 Terminology of Building ConstructionsE833 Terminology of Building EconomicsE1804 Practice for Performing and Reporting CostAnalysisDuring the Design Phase of a Project2.2 Other Standards:ANSI Z94.2-1989 Industrial Engineering Terminology:Cost Engineering4AACE Int

6、ernational Recommended Practice No 17R-97:Cost Estimate Classification System5AACE International Recommended Practice No 18R-97:Cost Estimate Classification System: As Applied in Engi-neering, Procurement, and Construction for the ProcessIndustries5AACE International Recommended Practice No 56R-08:C

7、ost Estimate Classification System As Applied inBuilding and General Construction Industries53. Terminology3.1 DefinitionsFor definitions of terms used in this prac-tice, refer to Terminology E833 and Terminology E631.4. Significance and Use4.1 Use of this classification will improve communicationam

8、ong all the stakeholders involved with preparing, evaluat-ing, and using cost estimates.4.2 The various parties that use cost estimates often misin-terpret the quality and value of the information available toprepare cost estimates, the various methods employed duringthe estimating process, the accu

9、racy level expected fromestimates, and the level of risk associated with estimates.4.3 This classification applies the degree of project defini-tion as the primary characteristic for determining an estimatesclassification.4.4 Using this classification will help those involved withproject estimates t

10、o avoid misinterpretation of the variousclasses of cost estimates and to avoid their misapplication andmisrepresentation. Improving communications about estimateclassifications reduces business costs and project cycle timesby avoiding inappropriate business and financial decisions,actions, delays, o

11、r disputes caused by misunderstandings ofcost estimates and what they are expected to represent.4.5 This classification is intended to be generic and soprovide a system for the classification of cost estimates in anyindustry. There are also references to specific industries, forcost estimate classif

12、ication as applied in: AACE International,Process Industry 18R-97, and AACE International, Building/General Construction Industry 56R-08.4.6 Estimate classifications provide valuable additional re-porting information when used as an adjunct to Practice E1804.1This specification is under the jurisdic

13、tion of ASTM Committee E06 onPerformance of Buildings and is the direct responsibility of Subcommittee E06.81on Building Economics.Current edition approved April 1, 2011. Published May 2011. Originallyapproved in 2006. Last previous edition approved in 2006 as E2516 06. DOI:10.1520/E2516-11.2This cl

14、assification is based on theAACE International Recommended Practices17R97, 18R-97, and 56R-09 pertaining to Cost Estimate Classification System.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards v

15、olume information, refer to the standards Document Summary page onthe ASTM website.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.5Available from the Association of the Advancement of Cost EngineeringInternational (AACE

16、International), 209 Prairie Avenue, Suite 100, Morgantown,WV 26501, http:/www.aacei.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Basis of Classification5.1 There are numerous characteristics that can be used tocategorize co

17、st estimate types. The most significant of these aredegree of project definition, end usage of the estimate, estimat-ing methodology, and the effort and time needed to prepare theestimate. The primary characteristic used in this guideline todefine the classification category is the degree of project

18、definition. The other characteristics are secondary.5.2 The discrete degrees of project definition used forclassifying estimates correspond to the typical phases and gatesof evaluation, authorization, and execution often used byproject stakeholders during a project life cycle.5.3 Five cost estimate

19、classes have been established. Whilethe degree of project definition is a continuous spectrum, it hasbeen determined from benchmarking industry practices thatthree to five discrete categories are commonly used. Fivecategories are established in this standard classification as it iseasier to simplify

20、 by combining categories than it is toarbitrarily split a standard.5.4 In Table 1 these estimate class designations are labeledClass 1, 2, 3, 4, and 5. A Class 5 estimate is based upon thelowest degree of project definition, and a Class 1 estimate isclosest to full project definition and maturity. T

21、his countdownapproach considers that estimating is an iterative processwhereby successive estimates are prepared until a final esti-mate closes the process.5.5 The five estimate classes are presented in Table 1 inrelationship to the identified characteristics. It is important tounderstand that it is

22、 only the degree of project definition thatdetermines the estimate class. The other four characteristics aresecondary characteristics that are generally correlated with thedegree of project definition.5.6 This generic matrix and guideline provides a high-levelestimate classification system that is n

23、on-industry specific. Theaccuracy ranges identified in Table 1 are indicated as indexvalues so that they may be applied generically to just about anyparticular industry. A more detailed explanation of these indexvalues, including two examples of their possible ranges, can befound in Appendix X1.6. D

24、etermination of the Cost Estimate Class6.1 The cost estimator makes the determination of theestimate class based upon the degree of project definition(design % complete). While the determination of the estimateclass is somewhat subjective, the design input data, complete-ness and quality of the desi

25、gn deliverables serve to make thedetermination more objective.7. Estimate Characteristics7.1 The following are brief discussions of the variousestimate characteristics used in the estimate classificationmatrix, Table 1. For the secondary characteristics, the overalltrend of how each characteristic v

26、aries with the degree ofproject definition (the primary characteristic) is provided.7.2 Degree of Project Definition (Primary Characteristic):7.2.1 This characteristic is based upon the level of comple-tion of project definition (roughly corresponding to the per-centage completion of architectural/e

27、ngineering detail anddesign). The degree of project definition defines maturity, orthe extent and types, of input information available to theestimating process. Such inputs include project scope defini-tion, requirements documents, specifications, project plans,drawings, calculations, knowledge and

28、 experience gained frompast projects, reconnaissance data, and other information thatmust be used, and developed, to define the project. Eachindustry will have a typical set of deliverables that are used tosupport the type of estimates used in that industry. The set ofdeliverables becomes more defin

29、itive and complete as thedegree of project definition (such as architecture and engineer-ing) progresses.7.3 End Usage (Secondary Characteristic):7.3.1 The various classes (or phases) of cost estimatesprepared for a project typically have different end uses orpurposes. As the degree of project defin

30、ition increases, the endusage of an estimate typically progresses from strategic evalu-ation and feasibility studies to funding authorization andbudgeting, to project control.TABLE 1 Generic Cost Estimate Classification MatrixPrimary Characteristic Secondary CharacteristicESTIMATEDCLASSDEGREE OFPROJ

31、ECTIONDEFINITIONEND USAGE METHODOLOGYEXPECTEDACCURACYRANGEPREPARATIONEFFORTExpressed as % ofcomplete definitionTypical purposeof estimateTypical estimating methodTypical 6 rangerelative to index of 1(that is, Class 1 estimate)ATypical degree of effortrelative to least costindex of 1BClass 5 0 % to 2

32、 % Screening or feasibility Stochastic (factors or models, or both)or judgment4to20 1Class 4 1 % to 15 % Concept study or feasibility Primarily stochastic 3 to 12 2 to 4Class 3 10 % to 40 % Budget authorizationor controlMixed but primarily stochastic 2 to 6 3 to 10Class 2 30 % to 70 % Control or bid

33、/tender Primarily deterministic 1 to 3 5 to 20Class 1 70 % to 100 % Check estimate or bid/tender Deterministic 1 10 to 100AIf the expected accuracy range index value of “1” represents +10/-5 %, then an index value of “10” represents +100/-50 %.BIf the preparation effort index value of “1” represents

34、 0.005 % of project costs, then an index value of “100” represents 0.5 %.E2516 1127.4 Estimating Methodology (Secondary Characteristic)7.4.1 Estimating methodologies fall into two broad catego-ries: stochastic and deterministic. In stochastic methods, theindependent variable(s) used in the cost esti

35、mating algorithmsare generally something other than a direct measure of the unitsof the item being estimated. The cost estimating relationshipsused in stochastic methods are often based on factors, metrics,models, etc. With deterministic methods, the independentvariable(s) are more or less a definit

36、ive measure of the itembeing estimated (can include, detailed takeoff, quotes, bids,etc.). A deterministic methodology reduces the level of conjec-ture inherent in an estimate. As the degree of project definitionincreases, the estimating methodology tends to progress fromstochastic to deterministic

37、methods.7.5 Expected Accuracy Range (Secondary Characteristic):7.5.1 Estimate accuracy range is an indication of the degreeto which the final cost outcome for a given project could varyfrom the estimated cost. Accuracy is traditionally expressed asa 6 percentage range around the point estimate, afte

38、r applica-tion of contingency, with a stated level of confidence that theactual cost outcome would fall within this range (6 measuresare a useful simplification, given that actual cost outcomeshave different frequency distributions for different types ofprojects). As the degree of project definition

39、 increases, theexpected accuracy of the estimate tends to improve, as indi-cated by a narrower 6 range.Additionally, industry experienceshows that a percentage range should also vary with the costmagnitude of the project. In addition to the degree of projectdefinition, estimate accuracy is also subj

40、ect to:7.5.1.1 Level of non-familiar technology in the project.7.5.1.2 Complexity of the project.7.5.1.3 Quality of reference cost estimating data.7.5.1.4 Quality of assumptions used in preparing the esti-mate.7.5.1.5 Experience and skill level of the estimator.7.5.1.6 Estimating techniques employed

41、.7.5.1.7 Time and level of effort budgeted to prepare theestimate.NOTE 1In Table 1, the values in the accuracy range column do notrepresent plus or minus percentages, but instead represent an index valuerelative to a best range index value of 1. If, for a particular industry, aClass 1 estimate has a

42、n accuracy range of +10/-5 percent, then a Class 5estimate in that same industry may have an accuracy range of +100/-50percent.NOTE 2Appendix A provides an illustrative example of estimateaccuracy ranges for two particular industries.7.6 Effort to Prepare Estimate (Secondary Characteristic):7.6.1 Th

43、e level of effort needed to prepare a given estimateis an indication of the cost, time, and resources required. Thecost measure of that effort is typically expressed as a percent-age of the total project costs for a given project size. As thedegree of project definition increases, the amount of effo

44、rt toprepare an estimate increases, as does its cost relative to thetotal project cost. The effort to develop the project deliverablesis not included in these effort metrics; they only cover the costto prepare the cost estimate itself.8. Relationships and Variations of EstimateCharacteristics: Discu

45、ssion8.1 There are a myriad of complex relationships that may beexhibited among the estimate characteristics within the esti-mate classifications. The overall trend of how the secondarycharacteristics vary with the degree of project definition wasprovided above. This section explores those trends in

46、 moredetail. Typically, there are commonalties in the secondarycharacteristics between one estimate and the next, but in anygiven situation there may be wide variations in usage, meth-odology, accuracy, and effort.8.1.1 The level of project definition is the driver of the othercharacteristics. Typic

47、ally, all of the secondary characteristicshave the level of project definition as a primary determinant.While the other characteristics are important to categorization,they lack complete consensus. For example, one estimatorsbid might be anothers budget. Characteristics such as meth-odology and accu

48、racy can vary markedly from one industry toanother and even from estimator to estimator within a givenindustry.8.2 Degree of Project Definition:8.2.1 Each project (or industry grouping) will have a typicalset of deliverables that are used to support a given class ofestimate. The availability of thes

49、e deliverables is directlyrelated to the level of project definition achieved. The varia-tions in the deliverables required for an estimate are too broadto cover in detail here; however, it is important to understandwhat drives the variations. Each industry group tends to focuson a defining project element that drives the estimate maturitylevel. For instance, chemical industry projects are processequipment-centric; such as, the level of project definition andsubsequent estimate maturity level is significantly determinedby how well the equipment is defined. Architectural p