Friday, September 21, 2007

Earned Value Management

One session of a conference I attended way back in March was a discussion about managing projects presented by Juval Löwy. One of Juval's excellent claims was that he had used earned value analysis to keep his management time to 15 minutes every Friday afternoon. He explained he used the rest of his time to become a better architect, and when he was finally too bored with the simplistic task of management, he moved on to architecture.

A great story, and certainly a compelling one for someone that needs to manage on less than 40 hours a week. I have been waiting to use this magical method, so as a recent project was ramping up, I pulled out my notes and hit a few websites to try and prepare for the 15 minute management job. Going on scant examples of exactly the type of project analysis I wanted caused this task to take somewhat more than 15 minutes. I found some helpful examples here and here.

If you aren't familiar with EV, the basic idea is that actual work is tracked against the amount of value accrued by the work completed against the plan of value to have been accrued according to the plan milestones. The notion of Earned Value has to do with tracking accomplished activities, rather than just time spent (I think this works well with my management objectives - I don't care how much time you spent, I care that the work gets done). Each activity has some percentage of value to the overall project. A simple way to get at this in software development is to divide the hours for one task against the total hours estimated for the project. Choosing the proper level of task granularity to track is a matter of balancing ease of reporting with meaningful levels of detail for catching problems before they go out of control. Once the earned percentage values are assigned to milestone tasks, you can either work with dollar figures or just work with hours - it doesn't matter. The important thing is to calculate how much earned value should be accrued at various key intervals along the project path. For instance, if I am checking in on my developers every Friday night, then I calculate EV earned to each Friday. When my developers report in, they tell me how many hours they worked this week, and what % complete they are for each milestone task.

Planned EV will be the number of developer hours available in the time period divided by the total number of project hours. When each developer reports a percent done, you multiply that by the percentage EV calculated for each task against which you are reporting. Summing each EV gives you the period EV which you compare against your goal. You can then use the total actual hours reported as a measure of how much real effort it took to get actual EV. This calculation comes into play as you forecast the future effort expenditure of the project. If you thought you could complete 10% EV with 80 hours, and got 8% EV with 80 hours, your SPI will give you a multiplier for estimating future period effort. This is where the 15 minutes comes in. Each Friday you must inspect your planned EV and and planned Costs against your actual's. You then analyze what variances in the charts mean to you:

  •  PEV way ahead of AEV? You underestimated and should add resources
  • AEV way ahead of PEV? - You overestimated and may be able to divert resources
  • AEV=PEV but costs overrun? - You can meet the deadline, but your resources are inefficient - you need to figure out what's bogging down your resources.
You get the idea. Manage next week's resources based on your 15 minutes of EV and cost analysis.

Without a tool to provide EV analysis for me, I turned to Excel. The only gotchas I had in setting up the calculations was discerning the best path for tracking - either project to date sums, or per period values; and getting graphs to show the EV and cost trends. In the end I went with per period values and some extra calculations to show trends and two separate graphs for EV and Cost.

With the plan in place, I simply communicated the project milestone tasks to the team along with target dates and requested weekly reporting of progress. Hopefully this leaves the devs with schedule freedom and a sense of autonomy, while giving me a way to know which adjustments are necessary before we have a big problem.

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1 comment:

Kiran said...


may I ask if you could publish the excel file you created for the Earned Value Analysis, for public download.