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Project is ahead of schedule and underspent.Labor BudgetBCWS60KDeadlinesv cv50K40KDate ofTimeAnalysisACWPcv = cost variancesv = schedule varianceBCWPAmerican Management Association • www.amanet.org152Fundamentals of Project ManagementResponding to VariancesIt is not enough to simply detect a variance.The next step is to understand what it means and what caused it.Then you have to decide what to do to correct for the deviation.Earlier, I explained that there are four responses that can be taken when there is a deviation from plan.Which of these you choose depends in part on what caused the deviation.Following are some general guidelines:៑ When ACWP and BCWP are almost equal and larger than BCWS (see Figure 11-5), it usually means that extra resources have been applied to the project, but at the labor rates originally anticipated.This can happen in several ways.Perhaps you planned for weather delays, but the weather has been good and you have gotten more work done during the analysis period than intended, but at the correct cost.Thus, you are ahead of schedule but spending correctly.៑ When ACWP and BCWP are nearly equal and belowBCWS (see Figure 11-6), it usually means the opposite of the previous situation; that is, you have not applied enough resources.Perhaps they were stolen from you, perhaps it has rained more than you expected, or perhaps everyone has decided to take a vacation at once.The problem with being in this position is that it usually results in an overspend when you try to catch up.៑ When ACWP is below BCWS and BCWP is above BCWS(see Figure 11-7), you are ahead of schedule and underspent.This generally happens because the original estimate was too con-servative (probably padded for safety).Another possibility is that you had a lucky break.You thought the work would be harder than it was, so you were able to get ahead.Sometimes it happens because people were much more efficient than expected.The problem with this variance is that it ties up resources that could be used on other projects.The economists call this an opportunity cost.There is also a good chance that if you were consistently padding estimates and were bidding against other companies on American Management Association • www.amanet.orgProject Control Using Earned Value Analysis 153projects, you probably lost some bids.If your competitor is using average values for time estimates while you are padding yours, then your figures are likely to be higher, and you will lose the bid.Acceptable VariancesWhat are acceptable variances? The only answer that can be given to this question is “It all depends.” If you are doing a well-defined construction job, the variances can be in the range of DŽ 3–5 percent.If the job is research and devel -opment, acceptable variances increase generally to around DŽ 10–15 percent.When the job is pure research, the sky is the limit.Imagine, for example, that you worked for a phar-maceutical company and your boss said, “Tell me how long it will take and how much it will cost for you to discover and develop a cure for AIDS.”For every organization, you have to develop tolerances through experience.Then you start trying to reduce them.All progress is an attempt to reduce variation in what we do.We will never reduce it to zero unless we eliminate the process altogether, but zero has to be the target.Using Percentage Complete toMeasure ProgressThe most common way to measure progress is to simply estimate percentage complete.This is the BCWP measure, but BCWP is expressed as a dollar value, whereas percentage complete does not make that conversion.When percentage complete measures are plotted over time, you tend to get a curve like the one shown in Figure 11-8.It rises more or less linearly up to about 80 or 90 percent, then turns horizontal (meaning that no further progress is being made).It stays there for a while; then, all of a sudden, the work is completed.American Management Association • www.amanet.org154Fundamentals of Project ManagementFigure 11-8. Percent complete curve.100CompletePercentTimeThe reason is that problems are often encountered near the end of the task, and a lot of effort goes into trying to solve them.During that time, no progress is made.Another part of the problem is in knowing where you are to begin with.We have already said that you are generally estimating progress.Consider a task that has a ten-week duration.If you ask the person doing that task where he is at the end of the first week, he is likely to tell you, “10 percent”; at the end of week two, “20 percent”; and so on.What he is doing is making a reverse inference.It goes like this: “It is the end of the first week on a ten-week task, so I must be 10 percent complete.” The truth is, he really doesn’t know where he is.Naturally, under such conditions, control is very loose.Still, this is the only way progress can be measured in many cases.American Management Association • www.amanet.orgProject Control Using Earned Value Analysis 155Key Points to Remember៑ Control is exercised by analyzing from the plan
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