SPI CPI Confusion

[Sameer]

Dear All;

I have a huge project plan and in that plan there are two tasks where the
CPI is around 3.0 and the SPI is 0.......
Is this sort of a situation possible? If yes then can anyone give me a
scenario where i can try to reproduce this?

Regards
Sameer

 

[davegb]

Are you sure that's what it's giving you? Unless there's a big glitch
in Project's EV calculations, somethings very wrong. For SPI to be 0,
EV would have to be zero. If EV is 0, then CPI would have to be 0.
Besides, an CPI of 3 is almost impossible. Basically it would mean
you're earned 3 times the value you've spent! Pretty hard to do, but
not quite impossible.

I haven't checked Project's EV calcuations for a while, so maybe there
is a new glitch I haven't heard of. Have you searched the MS database?

 

[Jim Aksel]

Probably what is happening is that SPI is very small. The value only shows
to two decimal places.

What this is saying is "I am way behind schedule, but I am certinly
accplishing a lot for the amount I have spent" If you have very little
accomplishment and very little spent, the ratios might become skewed.

Things that will drive these numbers: SPI=BCWP/BCWS. If you've made little
progress against a big baseline amount of scheduled work ....
CPI=BCWP/ACWP. If I divide BCWP by a small value for actual costs then CPI
becomes artificially large.

The driver to ACWP is Actual Cost of work .... that is driven by your rates
on the resource sheet. However, small rates also kill any meaning for BCWP
....

Also, make sure you are entering actual start/finsih dates for activitieis
in the "Actual Start" and "Actual Finish" date columns. This way, you will
take your EV when it is earned, not when it is scheduled.

Perhaps that helps.

 

[davegb]

Probably what is happening is that SPI is very small. The value only shows
to two decimal places.

Yes, and that would imply something terribly wrong here. If the value
only shows to 2 decimals, then, by deduction, the SPI must be less than
..005. If the EV is only $1000, pretty small on most projects, the
Budgeted Cost to this point would have to be $200,000! And, since the
CPI is about 3, the Actual Cost must be around $300! So he has a
project where he's planned to spend about $200,000 (or more) to this
point, has spend about $300, and has earned value of $1000. No matter
how you shake and bake these numbers, it tells me something is terribly
wrong somewhere.

 

[Sameer]

If i re-baseline the project everything works out fine...

 

[St Dilbert]

I'm not sure whether you want to re-baseline to "fix" this. In some
environments baselines are nearly sacred and you shouldn't re-save them
without at least two important signatures...

Though SPI and CPI are quite handy when it comes to judging status,
they can be a little confusing when drilled down to single activity
level.

In case you have a "way earlier than planned situation" your numbers
can be plausible:

1. Actual cost reported for last week on an activity i.e. ACWP >0, say
1 developer day for 500$
2. This is part of a effort estimated to take 6-developer days (3000$).
Since you have a huge plan, you might go for a simplified
0%-50%-100%-complete crediting approach for activities that are planned
to be finished in one or two reporting periods. This gives you a 50%
for work started i.e. BCWP=1.500$. i.e. CPI=3 for THIS SINGLE activity.
Not accurate but recommend practice for huge plans with many
activities.
3. The activity wasn't planned to start on or before the status date
(rare, but it happens, that e.g. Friday is already being worked on a
task planned to start monday). I.e. BCWS=0. Now this would in fact give
you an infinitely high SPI (division by zero). MSP replaces that with a
zero. Mathematically incorrect, but easier to handle with the data
types available for programming and probably also less confusing for
most users in most situations.

So the three core earned value fields are:
ACWP=500$; BCWS= 0; BCWP=1.500$ and are in my opinion all real,
plausible and realistic. SPI and CPI indices can also be interpreted if
you know the recommended practices as background. For using CPI and SPI
as management tools in huge plans I'd recommend looking at more summary
and cumulative levels (where most probably you won't have such erratic
numbers) and not touch the baseline.

Please note: above example may or may not fit your situation - I just
wanted to describe a situation where your numbers would be very
sensible.