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measuring delay with s curve

4 replies [Last post]
RAO RAO
User offline. Last seen 13 years 47 weeks ago. Offline
Joined: 5 Oct 2008
Posts: 13

Dear all,

please reply urgent.

how to measure delay using s curve i mean  we have early curve, late curve,actual curve.with the actual curve we compare the delay with early or late.

Regards,

rao

Replies

Rafael Davila
User offline. Last seen 18 weeks 15 hours ago. Offline
Joined: 1 Mar 2004
Posts: 5241

The flaws on using traditional EV is well known and documented, it has been suggested to update its use with the concept of an extension known as Earned Schedule.

From:

http://www.pmforum.org/library/second-edition/2011/PDFs/jan/SE-LIPKE.pdf

"The analysis indicates that the aberrant behavior of the EVM schedule indicators, SV and SPI, is overcome by employing the Earned Schedule (ES) computation methods. The application of Earned Schedule provides a set of schedule indicators, which behave correctly over the entire period of project performance."

I believe no method is perfect because there is no way to know the future, you can only forecast based on a set of assumptions, even probabilistic methods are just predictions whose predictions shall be updated continuously. Any method that is based on a fixed baseline is wrong.

If you look at my previous posting you will see two independent Banana Curves, one based on a Baseline perhaps an already obsolete baseline or an updated baseline and another set based on actual predictions using the updated schedule. In order to know where you are in comparison to original plan you must show all three banana curves, at minimum. I would say you should compare preferably in two separate diagrams the progress of your job. One diagram displaying the original baseline banana curves versus actual baseline and another comparing latest updated schedule banana curve against current/revised contractual baseline. Everyone knows the data displayed by S Curves is somewhat limited, just a birds-eye view and as such shall be interpreted, as something subject to change, as something dynamic.

Good management practice requires for the documentation and analysis of changes, it starts after your updates, it do not ends there.

Ian Dack
User offline. Last seen 5 years 22 weeks ago. Offline
Joined: 18 Apr 2008
Posts: 10

Hello Rao,

It's only if the costs being captured are are exactly the same as you had previously budgeted for where you can then measure progress.

However, this is very unlikely and you need to refer to your baselined programme to get this information.

Point for the future, your budget is firm and fixed at a given point from which to measure, the costs being incurred are variable but you should know the reasons why for reporting purposes.

Best wishes,

Ian

 

Rafael Davila
User offline. Last seen 18 weeks 15 hours ago. Offline
Joined: 1 Mar 2004
Posts: 5241

S Curves

I have seen many S Curves without the Projections shown, just the Baseline and Actuals, in such case you have less than zero.

In the above curve you can see actual at Data Date are near the average of early and late baselines curves but it does not tells you why the cost nor delay overruns, with the projection side you will see how much cost overrun and time delay is expected but not why. It is a birds-eye view and as such shall be interpreted. 

Mike Testro
User offline. Last seen 29 weeks 6 days ago. Offline
Joined: 14 Dec 2005
Posts: 4420

Hi Rao

It is not easy to measure delay using only an S Curve - particularly if it is cost generated - because there is no direct link between expenditure and progress.

The S Curve is an indication that delay has occurred but there is no demonstration of cause and effect.

Stick to the proven method of cause and effect on the critical path.

Best regards

Mike Testro