Does resource overallocation, past and present, affect the EVM fig

[Evan]

A client of mine had this question, and I had a halfway finished response,
but realized I needed cleverer minds that I to help me.

I have a master schedule that shows resources actuals overallocated in the
past. Since I let Project allocate the actual hours ( I enter them on a
weekly timescale) I will probably get numbers that have 10 hours one day, 2
hours the next and so on. As long as the weekly resource is not working over
40 hours a week, the EVM should not be affected I am guessing. Please let me
know if I am mistaken.

For future overallocations, I don't think the BCWP or BCWS is affected, but
the ETC might be. To me, that affect would be insignificant since the EAC
would stay the same if the total remaining work was correct, despite
overallocations at different intervals changing the slope of the ETC line
(graphed out in Excel).

I hope I am making sense, if I am please let me know if I am crazy in my
thought process.

 

[RTucker]

Your EVM figures are definetely affected by how you define, track and
calculate the Planned, % Complete and Actuals. Resource Allocation is, in a
way, independent of EVM calculations. The BCWS is defined by the
hours*$/day/resource to create the PMB. This is ignorant of the planned
utilization (8hrs/day) for each resource. However, when the %Complete and
actuals are entered to calculate BCWP and ACWP, if the resource cannot work
32 hours on four tasks in one day then SV/SPI and CV/CPI will show a slip.
From there, it's a slippery slope! Will it even out to a 1.0 to 40 hours
BCWS and BCWP at the end of the week? If you are allowing MSP to calculate
Actuals based on subjective %Complete values, then , your safe... You will
NEVER have a Cost overrun on your project. Congratulations!

Allowing MS Project to calculate Actuals is not good practice. How could
you ever experience an ACWP greater than the BCWP? You wont, therefore,
you're fooling yourself and the customer. If you slip and need to catch up
by creating a corrective action plan to work OT, where will it be shown?

As for Remaining Work...
Before you baseline, RW is equal to the entire planned effort (Work). If
you plan 40h Work, then report AW=30h, MSP will calculate the RW as 10h and
%Complete=75%. But what if after working 30 hours you realize the job is
bigger than you thought? You should manually change the RW to (say) 20h,
causing the %Complete to recalculate to 30/50, or 60% (not 75%). How does
this affect EVM? Well, BCWP=BCWScum*%Complete. You have only delivered 60%,
not 75% of the job. This is EFFORT based EVM, not duration-based EVM. It
greatly removes the harsh subjectivity of the EV method of "picking" a %
complete, and give a most accurate BCWP down to the task level!

If you maintain the Remaining Work instead of letting MSP under-calculate
it, then your ETC and EAC will be more accurate. Otherwise, they will rely
on 25% remaining EV, instead of the 40% that is really still open.

BOL,

RTucker, PMP

 

[Steve House [Project MVP]]

You're probably up on the following but for the benefit of others ...

Project will easily calculate ACWPs greater than BCWP. Here's how.
Resource Joe Fidmaker earns $10/hr and works 8hr/day. He's assigned to Task
X, 5 days duration starting Monday, to make 100 fids. Work is 40 mh, cost
is $400. We baseline and start work. BAC=$400. At the end of the 1st day
we're on schedule, BCWS=$80, BCWP=$80, ACWP=$80. So far so good. But
*WORK* is actually a measure of the effort required to achieve a given
output, not the time it takes - this means the BCWS is really the estimated
cost of 100 fids, the BWCP is the budgeted cost per fid times the number of
fids we have done up to the status date, while ACWP is the actual amount
we've spent for the time it took to produce however many fids we've made so
far. Coming up at the end of the day Friday, we find we've only done 50
fids, original estimate for duration was low by half so we update progress
by entering 5 days Actual Duration (time spent), 5 days Remaining Duration
(estimated required to complete) and MSP calculates 50% complete. As of
Friday 5pm, BCWS=$400, BCWP=$200, ACWP=$400 (because we still had to pay Joe
for the full 40 hours he worked even though it only generated 50 fids).
SPI=0.5, CPI=0.5, behind schedule and over budget. We work another week and
Joe finishes the 100th fid the following Friday. Now the *work* required to
make 100 fids is the same regardless of whether it takes 5 days or 10 and
thus the BCWS and BCWP don't increase beyond the baseline when the task runs
longer than the baseline estimate. At completion BCWS and BCWP are equal to
each other and also equal to BAC regardless of how long it took to get
there. But our ACWP *does* change since Joe doesn't put in those extra
man-hours for free. When the last fid is added to the pile at the end of 10
days duration, BCWS=$400, BCWP=$400, ACWP=$800, SPI=1, CPI=0.5. Project
happily calculates that for you IF you enter actual/remaining duration and
don't simply mark the task 100% done without entering actual performance.

 

[RTucker]

I agree that "work" is effort, but this is where any scheduling tool cannot
effectively capture the essence of the issue.

If I estimate (BCWS) that it will take two hours to dig a hole, then I
represent this as 2hrs of effort. Jumping to Phyiscs-101, it will take the
same amount of energy to move the dirt out of the hole ragardless of the
duration in which the work is expended.

OK. I 'work' harder (more sweating than planned), and I dig the hole in
1hr, instead of 2. Was more 'work' expended? Not according to Physics-101.
But according to MS project, I have:

BCWS=2
BCWP=1
ACWP=1
%Complete=100%
Therefore,
SV=1/2 (.5)
CV=1/2


Now, if I planned to charge $100 for the hole, and do charge $100, then:
BCWS=$100
BCWP=$50
ACWP=$100
Therefore,
SV=$50/$100 (.5)
CV=$100/$100 (1.0)

ANSI-748A allows you to track EVM using dollars, hours, or other measurable
units (2.2e), so either scenario can be realized. Which one is right? It
depends on who you are tracking EVM for, yourself or a customer.

 

[Steve House [Project MVP]]

Actually if you look at EV as MS Project 2003 computes it, your examples
aren't quite correct. Plug in a 1-task, 1-resource project and see. Even
though you've finished the hole in half the time, at completion BCWS and
BCWP are both equal and you did *2* hours worth of work (BCWP) in *1* hour
of time (ACWP) ...

BCWS = 2
BCWP = 2
ACWP = 1
SV = BCWP-BCWS = 0
CV = BCWP-ACWP = 1
SPI = BCWP/BCWS = 1.0
CPI = BCWP/ACWP = 2.0

When you dug the hole in 1 hour instead of 2, you didn't work harder, you
worked faster. The rate at which work is performed is the assignment units.
More work was not expended - the work remained the same but the units went
up, hence the duration went down.

If you draw a parallel to electrical consumption, "units" is equivalent to a
heater's wattage rating, "work" is the kilowatt-hours consumed to heat a
space, and "duration" is the time during which you operate the device.
--
Steve House [MVP]
MS Project Trainer & Consultant
Visit http://www.mvps.org/project/faqs.htm for the FAQs