《掙值法外文翻譯》word版

1、.1.外文原文THE EARNED VALUE CONCEPTThe earned value concept (sometimes also called achieved value) compares several measures to obtain an overall picture of project status. The following are the three primary data requirements:BCWS: Budgeted Cost of Work Scheduled: This measure, also called the project

2、plan, is developed at the outset of the project as it involves assigning to activities the amount budgeted (estimated) for every activity. Knowing the project schedule, it is possible to determine the amount of money budgeted relative to time. This is essentially the same as developing the cumulativ

3、e cost curve discussed earlier.BCWP: Budgeted Cost of Work Performed: This is the earned value as it indicates what the budgeted costs are for the work that has actually been performed to date. Note that this represents the periodic worth of the work that is actually performed, based on the initial

4、estimate, and has nothing to do with the actual costs incurred in performing the work. It requires making an assessment of the amount of work completed (time schedule) to date and then applying the appropriate budgeted amounts for this work.BAC: Budgeted Cost at Completion: This is the original cost

5、 estimate of the total cost of construction. It is ideally the total estimated cost to complete a project.EAC: Estimated Cost at Completion: This is the forecast of the total actual costs required to complete a project based on performance to date and estimates of future conditions.ACWP: Actual Cost

6、 of Work Performed: This is the measure that brings together the monitoring of both time schedule (work performed) and cost records (actual cost). It gives the actual costs to date. (Note that ACWS, Actual Cost of Work Scheduled, is not a component of the system, because if the work scheduled has no

7、t yet been performed, it is impossible to determine its actual cost!)Comparing the first (BCES) and last (ACWP) values to the earned value (BCWP) gives us an indication of “variances” from the expected.SV: Schedule Variances; BCWP-BCWS: Subtracting the budgeted cost of work scheduled from the budget

8、ed cost of work performed provides an indication of schedule deviance in terms of dollars of work. The cost side of the system remains constant (using budgeted cost figures) so the difference between the two amounts must be due to schedule deviations alone .A negative value indicates that the projec

9、t is behind schedule as the “value” of work performed is less than that schedule. This is shown graphically in Figure 10 .1.Note that the schedule deviance is presented in terms of dollars, while in reality this is an indication of project status in terms of scheduled time.SV=BCWP-BCWS (SV>0: ahe

10、ad of schedule, SV<0: behind schedule)CV: Cost Variance: BCWP- ACWP: The difference between the budgeted costs of work performed clearly indicates the status of the project in terms of cost. The work performed provides the common unit of comparison. A negative CV indicates the project is over bud

11、get as the actual costs exceed the budgeted costs. This is shown graphically in Figure 10 .2.CV= BCWP- ACWP (CV>0:under budget, CV<0: over budge)These variances can be further expressed as ratios in percentage figures: % SV:% Schedule Variance: 100 × SV/BCWS: This ratio indicates the perc

12、ent deviation from the schedule based on budgeted cost values.% CV:% Cost Variance: 100 × CV/BCWP: This measure gives the percentage deviation from the actual costs from what was budgeted for the work performed to date. Figure 10.1 Earned Value Analysis Showing a Project that Is Ahead of Schedu

13、le Similarly, cost and schedule indicators can be measured as:SPI: Schedule Performance Index: BCWP/BCWS: This ratio provides a direct relationship between work performed and work scheduled based on budgeted costs. A value greater than 1.0 indicates that more work has been performed than was schedul

14、ed, and thus the project is ahead of schedule.SPI=BCWP/BCWS (SPI>1: ahead of schedule, SPI<1: behind schedule)CPI: Cost Performance Index: BCWP/ACWP: This ratio directly compares budgeted costs to actual costs based on work performed. A value greater than 1.0 indicates that the budgeted amount

15、 of the work is higher than what it actually cost, and therefore the project is under budget. Since dollars are not represented in the CPI, the results are sometimes easier to interpret.CPI=BCWP/ACWP (CPI>1: under budget, CPI<1: over budget)It can be expected that these performance indices wil

16、l show variations throughout the life of the project. Generally, it can be expected that the indices will be less than 1.0 early in the project and rise as the project progresses. This is due to start-up and “l(fā)earning curve” factors that normally inhibit efficient operations early in a project. If c

17、alculated separately for each time period, the values may also show a ragged series of peaks and values. Calculating a cumulative index from project start to date shows a smoother transition and over time should approach 1.0 for a project that is close to schedule and budget.Figure 10.2 Earned Value

18、 Analysis Showing a Project that Is Over BudgetDetermining the status of percent complete of a project can also be accomplished with the variables already defined. The percent complete (PC) is simply the ratio BCWP/BAC, expressed as a percent. Note that this assessment merely defines the percent com

19、pletion based on original estimates and is not influenced by actual cost figures. Another way of viewing earned value (BCWP) is gives in the following expression:Earned Value=(PC)×(BAC)The percent completion can be compared with the expected or anticipated percent completion at a given point in

20、 time. The planned percent complete (PPC) is derived at a point in time with the ratio BCWS/BAC, expressed as a percent. The PPC is easy to grasp as a measure of the project status when compared to the PC. For example, if the PPC is determined to be 60% and the PC is determined to be 65%, it is clea

21、r that the project is running ahead of schedule.Information on the cost index and how it has changed over time can be used to forecast what the costs will be at the end of the project, referred to as Estimated at Completion (EAC). The forecast of the EAC can also be obtained at a given point in time

22、 with the variables that have already been defined. A simple computation of the EAC at a given point in time is computed as follows:EAC=ACWP+ (BAC-BCWP) where BAC-BCWP represents unearned hours The EAC is the latest revised of the total cost of the project and can be compared to the BAC (original es

23、timated project cost) to determine an estimated At Completion Variance (ACV). Since the EAC is based on costs incurred to date, this estimate will be accepted as being more accurate than the BAC. The ACV is a simple computation and provides an estimate of the amount (ACV-EAC). Id ACV>1, the proje

24、ct is expected to overrun or exceed the budget. Because of the importance of the value of ACV, it is important that the determination of EAC be as accurate as possible. The projection of EAC may use a cumulative average CPI, the CPI for the most recent period, or some other selected figure. Applying

25、 the selected CPI ratio to the BAC value will yield an estimated EAC (EAC=BAC/CPI).ExampleA simple problem will help to illustrate the application of the principles of earned value. A project has been defined that consists of 12 activities (each requires one month to complete) for which the estimate

26、d costs and durations have been defined (see Figure 10.3).The project costs are estimated to $257,000(BAC = sum of the costs of all activities). The project is scheduled to be completed in six months. After three and a half months, the site work, excavation, foundation, fencing, and rough electrical

27、 work are completed. The framing is one-half complete, the rough plumbing is three-fourths complete, and the paving is half complete. The incurred costs to date are$152,000. What is the status of this project in terms of the schedule and the budget?ACWP = $152,000 (given)BCWS = ($22,000+$30,000+$50,

28、000+$10,000+$18,000)+1/2×($40,000+$6,000+$16,000) = $161,000BCWP = ($22,000+$30,000+$50,000+$10,000+$6,000)+1/2×($40,000)+$3/4($16,000) +1/2×($18,000)=$159,000Project status: Schedule Variance = BCWP-BCWS = $159,000-$161,000=-$2,000 SPI = BCWP/ BCWS = $159,000/$161,000=0.99% Schedule

29、Variance: 100×SV/ BCWS = 100×($2,000/$161,000)=-1.2%Slightly behind scheduleCost Variance = BCWP- ACWP = $159,000-$152,000=$7,000 CPI = BCWP/ACWP = $159,000/$152,000=1.05% Cost Variance:100×CV/BCWP =100×($7,000/$159,000)=+4.4% Below budgetPercent Complete = BCWP/BAC×100%=$15

30、9,000/$257,000×100% =62% completeEAC = ACWP + (BAC- BCWP) =$152,000 +($257,000-$159,000) =$250,000ActivityCostMonth 1Month 2Month 3Month 4Month 5Month 6Sitework22,000Fencing10,000Paving18,000Excavation30,000Foundation50,000Framing40,000Rough electric 6,000Rough plumbing16,000Drywall13,000Suspen

31、d ceiling 4,000Interior finish34,000Carpeting14,000Figure 10.3 Schedule of Activities and Their Associated CostsAlthough the project is slightly behind schedule, it is performing under budget. The project is currently at the 62% completion stage and is estimated to be completed for a revised estimat

32、ed cost of $250,000, a decrease from the original estimate.2.外文翻譯掙值法的概念掙值法的概念（有時也被稱為實現(xiàn)價值）比較幾種措施獲得一個全面的了解項目狀態(tài)。以下是三種主要的數(shù)據(jù)要求：BCWS:計劃工作預算成本：這一措施，也被稱為項目開發(fā)計劃，在項目一開始就涉及分配活動的預算額（估計）的每一個活動。了解項目進度，它有可能確定的數(shù)額的金錢預算相對時間。這是基本相同的累計成本曲線前面討論的發(fā)展。BCWP:已完成工作的預算成本：這是掙值說明什么預算成本的工作，實際上已完成日期。注意，這是周期性的工作，實際上是執(zhí)行，根據(jù)初步估計，并沒有實際發(fā)

33、生的費用進行工作。它需要做出評估完成的工作量（時間）的日期和運用適當?shù)念A算數(shù)額為這項工作。BAC：竣工預算費用：這是用原來的成本估計總建筑成本。它是理想的總費用估計完成項目。EAC：估計完工成本：這是預測的總實際成本在完成項目所需的性能的基礎(chǔ)上的日期和估計未來的條件。ACWP:已完成工作實際成本：這是衡量，匯集了監(jiān)測的時間安排（工作）和成本記錄（實際成本）。它的實際成本日期。（注意，ACWS，工作的實際成本，不是一個系統(tǒng)的組成部分，因為如果工作計劃尚未完成，這是不可能的，以確定其實際成本?。┍容^第一（BCES）和最后（ACWP）值的掙值（BCWP）給了我們一個指示“差異”的預期:SV：進度差異

34、；BCWP-BCWS：減去計劃工作預算成本的完成工作的預算成本提供了一個顯示進度偏差的工作。成本方面的系統(tǒng)保持不變（使用預算成本數(shù)據(jù)），兩者間差異的數(shù)量必須是由于進度偏差的。負值表示項目進度落后的“價值”的工作是低于計劃。這些圖形顯示在圖10。1. 請注意，進度偏差是從美元，而實際上這是一個顯示項目狀況方面的計劃時間。SV= BCWP-BCWS（SV> 0：進度提前，SV< 0：進度落后）CV：成本差異：BCWP-ACWP:之間的差額預算費用進行的工作清楚地說明，成本方面在項目的地位。工作提供了共同單位比較。一個負面的CV說明，該項目是在預算和實際費用超出預算成本。這些圖形顯示在圖

35、10。2。CV=BCWP-ACWP（CV>0：預算節(jié)支，CV<0：超過預算）這些差異可以進一步用表示比率的百分比數(shù)字表示：%SV：%進度差異：100×SV/BCWS：這一比率說明在百分偏差的時間表的基礎(chǔ)上偏離預算成本值。%CV：%成本差異：100×CV/BCWP：這項措施的百分比偏離實際費用預算執(zhí)行工作的日期。同樣地，成本和進度指標也能進行衡量：SPI：進度績效指標：BCWP/BCWS：這個比例提供之間直接關(guān)系的工作表現(xiàn)和工作計劃的基礎(chǔ)上的預算費用。大于1的值說明，更多的工作已經(jīng)完成，比原定，項目進度提前。圖10.1凈掙值分析顯示，項目，計劃之前SPI=BCWP

36、/BCWS（SPI> 1：進度提前，SPI< 1：進度落后）CPI：成本績效指數(shù)：BCWP/ACWP：這在直接比較預算成本實際成本的基礎(chǔ)上完成的工作。大于1的值說明，預算金額的工作是高于它的實際成本，因此該項目是在預算。由于美元沒有代表的消費物價指數(shù)，有時結(jié)果容易解釋。CPI=BCWP/ACWP（CPI> 1:低于預算，CPI< 1:高于預算）可以預料，這些指標將顯示的變化在整個項目周期。一般來說，可以預計，指數(shù)小于1的早期項目，作為項目的進展。這是由于啟動和“學習曲線”因素，通常抑制高效運作項目初期。如果計算分別為每個時間段的價值，也可能出現(xiàn)參差不齊的山峰和價值觀系列

37、。一個累積計算指數(shù)從項目開始日期顯示的順利過渡和時間應為1，接近項目進度和預算。確定地位的完成百分比的一個項目，也可以實現(xiàn)與已定義的變量。完成百分比（PC）只不過是比項目，表示為百分之一。注意，這一評估僅定義了%的基礎(chǔ)上完成原先的估計和不影響實際成本數(shù)據(jù)。另一個方式看掙值（BCWP）是在下面的表達式：掙值=（PC）×（BAC）完成的百分比可以比較與預期的或預期的完成百分比在特定時間點。計劃完成百分比（PPC）是在一個時間點的比例BCWS/BAC，表示為百分之一。競價排名是很容易掌握作為衡量項目的狀況完成百分比。例如，如果計劃完成百分比被確定為60%和完成百分比被確定為65%，很明顯，項目運行計劃之前。圖10.2凈掙值分析顯示，項目，超過預算信息的成本指標和如何隨時間的變化可以用來預測成本將在項目結(jié)束時，稱為估計完成（EAC）。預測的東非共同體也可以得到在特定時間點的變量已被定義。一個簡單的計算EAC在特定的時間點的計算如下：EAC=ACWP+（BAC-BCWP）在BAC-BCWP 代表未到期時間估計完成最新修訂的總成本的項目可以比較的估計完成（原估計工程費用）來確定估計完成方差（在完成方差）。由于成本是根據(jù)日期來估計完成的，這估計將被認為是