Study EVM (Earned Value Management) – 2

Once the CPI/SPI were calculated at some time-stamp, project manager should be deeper analyses, he need to predict the future cost:

ETC (Estimate To Completion)

Then EAC (Estimate At Completion) = AC + ETC

How to calculate ETC based on current situation (EV/AC/PV and SPI&CPI), there are usually three methods:

  1. Regardless of current Schedule/Cost Performance Index
    This way is simple, I don’t care what’s happened, EAC = BAC + EAC – AC, in other words, project team is confident to finish the project below estimated cost.
  2. Estimated based on current CPI
    This way is straight-forward, review current CPI and estimate future cost based on it:
    EAC = AC + (BAC -EV)/CPI = BAC / CPI
  3. Consider both CPI/SPI impact
    I think this way the rationalist one, it consider both SPI and CPI, in additional, PM could give a “weight” to SPI or CPI according to his/her experience and judgement, so the formula is:
    EAC  = (BAC – EV) / (CPI * SPI)

No matter which method PM chooses, as long as the calculated/predicted EAC is not acceptable, then it is an “early warning” to the team.

Even more, PM need calculate TCPI, the content below as copied from EVM on Wikipedia, it is very clear for me.

The To Complete Performance Index (TCPI) provides a projection of the anticipated performance required to achieve either the BAC or the EAC.

For the TCPI based on BAC (describing the performance required to meet the original BAC budgeted total):
TCPI_{BAC} = { BAC - EV \over BAC - AC }
or for the TCPI based on EAC (describing the performance required to meet a new, revised budget total EAC):
TCPI_{EAC} = { BAC - EV \over EAC - AC }
Independent estimate at completion (IEAC)
The IEAC is a metric to project total cost using the performance to date to project overall performance. This can be compared to the EAC, which is the manager’s projection.
IEAC = \sum AC + { \left( BAC - \sum EV \right) \over CPI }

Wish I success, again!  +U!

Study EVM (Earned Value Management) – 1

During the past few days I was studying Project Time Management in PMBOK, for preparing the upcoming PMP exam on 4th December 2010, while I spent a few hours on understanding/mastering EVM, I log my memory hereSmile

EVM stands for Eearned Value Management, it is a complementary for Critical Path Method schedule management, its purpose could be described as “What did we get for the money we spent?” the definition of is in Wikipedia is below:

Earned value management (EVM) is a project management technique for measuring project progress in an objective manner. EVM has the ability to combine measurements of scope, schedule, and cost in a single integrated system. When properly applied, EVM provides an early warning of performance problems. Additionally, EVM promises to improve the definition of project scope, prevent scope creep, communicate objective progress to stakeholders, and keep the project team focused on achieving progress.

There are three fundamental glossaries in EVM, they are:

  • PV Plan Value (also called BCWS – Badget Cost for Work Scheduled)
  • AC Actual Cost (also called ACWP – Actual Cost for Work Performed)
  • EV Earned Value (also called BCWP Badget Cost for Worked Performed), so
    EV = BAC (Budget At Completion) * [Finished work]%
    EV formula from Wikipedia:


For simple and straight-forward, in my understanding:

  • PV is on a specified timestamp, what is the planed budget.
  • AC is on a specified timestamp, what is the actual cost.
  • EV is on a specified timestamp, how much percent of work has been done while how much cost was expected.
    During the project implementing process, Program Manager tracks the schedule and cost using EVM, and calculate SV&SV, SPI&CPI, they are:

SV Schedule Variance
SV = EV – PV
CV Cost Variance
CV = EV – AC

SPI Schedule Performance Index
CPI Cost Performance Index

I take a simple example for better understanding, assume I am managing a 10 days project code name “Lambda”, Lambda project has a BAC of $100, and the detailed project schedule was determined below:

Day# 1 2 3 4 5 6 7 8 9 10
Budget $10 $10 $10 $10 $10 $10 $10 $10 $10 $10

The scenario is at the end of day 3, I (PM) called up team member and held a meeting to track status, we found:

We got 40% of the entire work done, on the other hand, we’ve already spent $60, based on this fact, I (PM) will get to know:

PV: 3 days past, initially we planed/supposed to spend $30 according to the schedule, so PV=30.
AC: We’ve spent &60, so AC=60.
EV: we finished 40% of work, initially we planed/supposed to spend $40 to get 40% work done, so EV=40

OK, then:

SV = EV – PV = 40 – 30 = 10, greater than 0, it is good, we are ahead scheduleSmile
CV = EV- CV = 40 – 60 = -20, smaller than 0, it is not good, we are overspending moneySad smile

SPI = EV/PV = 40/30 = 1.3 > 1 greater than 1, good.
CPI = EV/CV = 40/60 = 0.66 < 1, smaller than 1, not good.

+U+U to myself, I put a flag here, I believe I will pass the exam!


EVM on Wikipedia

EVM official web site