ASTM E2516-2006 Standard Classification for Cost Estimate Classification System《成本估计分类系统的标准分类》.pdf

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1、Designation: E 2516 06Standard Classification forCost Estimate Classification System1, 2This standard is issued under the fixed designation E 2516; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number

2、 in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 c

3、ost estimates.1.2 This classification maps the phases and stages of costestimating to a generic maturity and quality matrix, keyed to alevel 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

4、 provides 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. Refer

5、enced Documents2.1 ASTM Standards:3E 631 Terminology of Building ConstructionsE 833 Terminology of Building EconomicsE 1804 Practice for Performing and Reporting Cost Analy-sis During the Design Phase of a Project2.2 Other Standards:ANSI Z94.2-1989 Industrial Engineering Terminology:Cost Engineering

6、4AACE International 17R-97 Recommended Practice: CostEstimate Classification System5AACE International 18R-97 Recommended Practice: CostEstimate Classification System: As Applied in Engineer-ing, Procurement, and Construction for the Process Indus-tries53. Terminology3.1 DefintionsFor definitions of

7、 terms used in this prac-tice, refer to Terminology E 833 and Terminology E 631.4. Significance and Use4.1 Use of this classification will improve communicationamong all the stakeholders involved with preparing, evaluat-ing, and using cost estimates.4.2 The various parties that use cost estimates of

8、ten misin-terpret the quality and value of the information available toprepare cost estimates, the various methods employed duringthe estimating process, the accuracy level expected fromestimates, and the level of risk associated with estimates.4.3 This classification applies the level of project de

9、finitionas the primary characteristic for determining an estimatesclassification.4.4 Using this classification will help those involved withproject estimates to avoid misinterpretation of the variousclasses of cost estimates and to avoid their misapplication andmisrepresentation. Improving communica

10、tions about estimateclassifications reduces business costs and project cycle timesby avoiding inappropriate business and financial decisions,actions, delays, or disputes caused by misunderstandings ofcost estimates and what they are expected to represent.4.5 This classification is intended to be gen

11、eric and soprovide a system for the classification of cost estimates in anyindustry.4.6 Estimate classifications provide valuable additional re-porting information when used as an adjunct to PracticeE 1804.5. Basis of Classification5.1 There are numerous characteristics that can be used tocategorize

12、 cost 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 proj

13、ectdefinition. The other characteristics are secondary.1This specification is under the jurisdiction of ASTM Committee E06 onPerformance of Buildings and is the direct responsibility of Subcommittee E06.81on Building Economics.Current edition approved Oct. 1, 2006. Published October 2006.2This class

14、ification is based on the Cost Estimate Classification System,Recommended Practice Document AACE International 17R97.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to

15、 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), 209 Prairie Avenue, Suite

16、 100, Morgantown, WV 26501,USA.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 The discrete levels of project definition used for classi-fying estimates correspond to the typical phases and gates ofevaluation, authorization, and

17、execution often used by projectstakeholders during a project life cycle.5.3 Five cost estimate classes have been established. Whilethe level of project definition is a continuous spectrum, it hasbeen determined from benchmarking industry practices thatthree to five discrete categories are commonly u

18、sed. Fivecategories are established in this standard classification as it iseasier to simplify by combining categories than it is toarbitrarily split a standard.5.4 In Fig. 1 these estimate class designations are labeledClass 1, 2, 3, 4, and 5. A Class 5 estimate is based upon thelowest level of pro

19、ject definition, and a Class 1 estimate isclosest to full project definition and maturity. This 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 Fig.

20、1 inrelationship to the identified characteristics. It is important tounderstand that it is only the level of project definition thatdetermines the estimate class. The other four characteristics aresecondary characteristics that are generally correlated with thelevel of project definition.5.6 This g

21、eneric matrix and guideline provides a high-levelestimate classification system that is non-industry specific. Theaccuracy ranges identified in Fig. 1 are indicated as indexvalues so that they may be applied generically to just about anyparticular industry. A more detailed explanation of these index

22、values, including two examples of their possible ranges, can befound in Appendix X1.6. Estimate Characteristics6.1 The following are brief discussions of the variousestimate characteristics used in the estimate classificationmatrix, Fig. 1. For the secondary characteristics, the overalltrend of how

23、each characteristic varies with the degree ofproject definition (the primary characteristic) is provided.6.2 Level of Project Definition (Primary Characteristic)6.2.1 This characteristic is based upon the level of comple-tion of project definition (roughly corresponding to the per-centage completion

24、 of architectural/engineering detail anddesign). The level of project definition defines maturity, or theextent and types, of input information available to the estimat-ing process. Such inputs include project scope definition,requirements documents, specifications, project plans, draw-ings, calcula

25、tions, knowledge and experience gained from pastprojects, reconnaissance data, and other information that mustbe used, and developed, to define the project. Each industrywill have a typical set of deliverables that are used to supportthe type of estimates used in that industry. The set ofdeliverable

26、s becomes more definitive and complete as the levelof project definition (such as architecture and engineering)progresses.6.3 End Usage (Secondary Characteristic)6.3.1 The various classes (or phases) of cost estimatesprepared for a project typically have different end uses orpurposes. As the level o

27、f project definition increases, the endNOTE 1a If the expected accuracy range index value of “1” represents +10/-5 %, then an index value of “10” represents +100/-50 %.NOTE 2b If the preparation effort index value of “1” represents 0.005 % of project costs, then an index value of “100” represents 0.

28、5 %.FIG. 1 Generic Cost Estimate Classification MatrixE2516062usage of an estimate typically progresses from strategic evalu-ation and feasibility studies to funding authorization andbudgeting, to project control.6.4 Estimating Methodology (Secondary Characteristic)6.4.1 Estimating methodologies fal

29、l into two broad catego-ries: stochastic and deterministic. In stochastic methods, theindependent variable(s) used in the cost estimating algorithmsare generally something other than a direct measure of the unitsof the item being estimated. The cost estimating relationshipsused in stochastic methods

30、 often are somewhat subject toconjecture. With deterministic methods, the independent vari-able(s) are a more definitive measure of the item beingestimated. A deterministic methodology is not subject tosignificant conjecture. As the level of project definition in-creases, the estimating methodology

31、progresses from stochas-tic to deterministic methods.6.5 Expected Accuracy Range (Secondary Characteristic)6.5.1 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 perc

32、entage range around the point estimate, after 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 ofpr

33、ojects). As the level of project definition 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. Typically a range will narrow as th

34、ecost magnitude increases, for example a 10 % range on100 000 job may be unrealistically narrow, whereas a 10 %range for a $100 000 000 job may be considered absurdlywide.NOTE 1In Fig. 1, the values in the accuracy range column do notrepresent plus or minus percentages, but instead represent an inde

35、x valuerelative to a best range index value of 1. If, for a particular industry, aClass 1 estimate has an 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

36、 ranges for two particular industries.6.6 Effort to Prepare Estimate (Secondary Characteristic)6.6.1 The 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 p

37、roject costs for a given project size. As thelevel of project definition increases, the amount of effort 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 cos

38、tto prepare the cost estimate itself.7. Relationships and Variations of EstimateCharacteristics: Discussion7.1 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 secondarycharacteristi

39、cs vary with the level of project definition wasprovided above. This section explores those trends in 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, accura

40、cy, and effort.7.1.1 The level of project definition is the driver of the othercharacteristics. Typically, 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. F

41、or example, one estimatorsbid might be anothers budget. Characteristics such as meth-odology and accuracy can vary markedly from one industry toanother and even from estimator to estimator within a givenindustry.7.2 Level of Project Definition7.2.1 Each project (or industry grouping) will have a typ

42、icalset of deliverables that are used to support a given class ofestimate. The availability of these 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 importan

43、t 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

44、significantly determinedby how well the equipment is defined. Architectural projectstend to be structure-centric, software projects tend to befunction-centric, and so forth. Understanding these drivers putsthe differences that may appear in the more detailed industryaddenda into perspective.7.3 End

45、Usage7.3.1 While there are common end usages of an estimateamong different stakeholders, usage is often relative to thestakeholders identity. For instance, an owner company may usea given class of estimate to support project funding, while acontractor may use the same class of estimate to support ac

46、ontract bid or tender. It is not at all uncommon to findstakeholders categorizing their estimates by usage-relatedheadings such as budget, study, or bid. Depending on thestakeholders perspective and needs, it is important to under-stand that these may actually be all the same class of estimate(based

47、 on the primary characteristic of level of project defini-tion achieved).7.4 Estimating Methodology7.4.1 As stated previously, estimating methodologies fallinto two broad categories: stochastic and deterministic. Thesebroad categories encompass scores of individual methodolo-gies. Stochastic methods

48、 often involve simple or complexmodeling based on inferred or statistical relationships betweencosts and programmatic or technical parameters, or both.Deterministic methods tend to be straightforward counts ormeasures of units of items multiplied by known unit costs orfactors. It is important to rea

49、lize that any combination ofmethods may be found in any given class of estimate. Forexample, if a stochastic method is known to be suitablyaccurate, it may be used in place of a deterministic methodeven when there is sufficient input information based on theE2516063level of project definition to support a deterministic method.This may be due to the lower level of effort required to preparean estimate using stochastic methods.7.5 Expected Accuracy Range7.5.1 The accuracy range of an estimate is dependent upona number of characteristics of the estimate input informationand