Percent Complete vs. Percent Work Complete in Earned Value Calculations

[David Oliver]

It seems MSP uses % complete rather than % work complete
to compute earned value from planned value for a task or
project. This doesn't make sense to me given that
planned value is work X resource rate and %complete is
really a measure of duration rather than work. It's like
comparing apples and oranges. Using %complete instead of
%work complete also really skews the earned value on
partially completed tasks that have been split during
schedule statusing (Tools/Tracking/Update
Project/Reschedule uncompleted work to start after...)

So I am wondering if MSP provides a configuration option
that allows you to use %work complete to compute earned
value (BCWP), and consequently spi and cpi? Can anyone
help with that? Thanks in advance to anyone who replies
to this question!

 

[JulieS]

David,

In Project 2002 and 2003 you can change the earned valued
calculation from % complete to physical % complete.
The physical % complete is a user entered value.
To switch to physical % complete:
Tools --> Options
Calculation tab
Click on the earned value button.

The other option would be to use custom fields with
formulas to calculate the earned value data based upon %
Work complete.

Hope this helps.
Julie

 

[Steve House]

Not quite so far fetched when you consider the default behavior of MSP is to
update work at the same rate at which it updates duration, unless you switch
it off in options. When you say that a 5 day duration task is 50% complete
you will be setting the work completed to what ever value should have been
done by the 50% duration mark. If it was a straightline 40 hour assignment,
50% duration will show up as also 50% work complete. If the task is
contoured, lets say 5 day duration with 1 hour on each of Mon, Tue, Wed,
Thur and 8 hours Fri for a total of 12 hours of work, 50% complete will show
we're at noon on Wed and as of this point we have done 2.5 hours of work for
21% work complete. Entering % Complete then indirectly computes the work
done as it was initially estimated and baselined and the BCWP reflects the
total work to have been performed after a duration equal to the % Complete.

Also, the SPI is a description of *schedule* performance not work. If the
SPI = 1, the duration we've actually worked up to the status date is equal
the duration represented by the status date. If it's <1, the duration
worked is what we would have done at some prior status date were we actually
on schedule. If we're behind schedule on 15 May, the BCWS will reflect the
work that would have been done were we 100% in line with our duration while
the BCWP relects the 100% duration level for a date equal to the status date
+ schedule variance. % Work Complete is actually more allied to the ACWP
than it is the BCWP as it reflects, among other things, how much work was
actually required for the tasks compared to how much we had estimated would
be required.