Hi,

neg. SV does not mean we are behind schedule in terms of target date at the moment.
But it shows us there are some delay, and the schedule have high probablity of delay in future.
Some activites are consuming the float of the schedule, more activities trends to be critical.
We may have more problem with resource management.

thinking of 2 schedules (both of them have no delay on critical path),which is better?

1. zero SV, 100 remaining activities, 30% on critical path
2. Neg SV, 100 remaining activities, 45% on critical path

Remember that all of these indicators are there to help us see the trends of where a project is heading. It is often best to listen to what each of the indicators is telling us and make a reasoned judgement based on all. Planning is more of an art than a science and subjective and open to interpretation.

Yes, Vladimir you are right; that is what Schedule Variance is said to be a subjective indicator.

Hi Alex
Their is a Direct Relationship between SV and On Schedule. for your SV to be Negative something must be later than planned. (Not Necasary the CP).

Wat happens if your planned line is based on your late Dates ???. IF your SV is negative you are late. (Not just behind schedule) What if all your activities is Critical again you are late if your SV is Negative.

Cheers

Hi Alex if you have a project with a variable Budget (Normally used in a cost plus type contract)you would use Earned Value with a Variable budget.

It does not change things much except you will have a variable Budget (Qauntity Adjusted Budget).

Cheers

Hi Alex

I from what do you calculate your earned value from your Budget. (Fixed or Variable) Remember it is Earned and Not Actual.

% Work Completed x Budget.

BCWS
BCWP
ACWS
ACWP

Alex

Their is a variance between Earned Value and Actual value.

Please note we are only discussing Earned Value on fixed Budget.

If you do earned Value on veriable budget you would have a QAB. (This is not very different)

Cheers

Hi Dinesh,

Sure without completing the non-critical activities we can’t finish the project, but the EV1 & EV2 values are given in the example is meant for some % of Overall Budgeted cost during the point in time not at the end of the project, (refer Renee’s initial Post) hope this will clear your doubt.

in addition to yours, you can add the following, SPI=BCWP/BCWS, CPI=BCWP/ACWP, SCI=SPI*CPI, TCPI=(BAC-BCWP)/(BAC-ACWP) etc etc...........

It is worth to refer Vladimir’s Presentation............

Cheers!!

Daya

Jaco, let’s define what is on schedule. Defining schedule is a separate topic.
Being on schedule means that your actual and planned dates are on or ahead of target dates, if your actual and planned dates are behind target dates then you are behind schedule.
If to use more complex approach with the risk simulation then you are on schedule if the probabilities to meet target dates are higher than initial and you are behind schedule if some of these probabilities are lower.

We shall define what is behind schedule.
First of all no project will be on schedule - you are not able to do all activities just in time because there is always some uncertainty.
If we are late with the critical activities and the prognosed project finish is late you are certainly behind schedule even if you have done some non-critical activity faster than was expected. If this non-critical activity was expensive then your CV will be positive.
If you are successful with the critical activities (ahead of schedule) and for some reason postponed an activity that has large float it does not mean that you are behind schedule though your CV may be negative.
I think that being behind schedule means that some target dates may be violated and not that you spend less money than expected delaying activities that have sufficient float.
Resource example:
Your project consists of two parallel activities of the same duration executed by two different resources, one is expensive and another cheap. Expensive resource works faster than expected, cheap one - slower. You may have excellent positive CV for some time but your project finish will be delayed. And CV will not show that there is a problem for too long!
Regards,
Vladimir

Jaco,
I think that Daya’s example is good and explains the problem.
I want to add some thoughts about limited resources. My experience shows that resources are always limited though not all of them. You cannot use unlimited number of cranes on the construction site, you may have limited number of skilled programmers, you have restricted finances and some schedule of supplies. You may have unlimited resources also (you can hire necessary number of construction workers, etc.). If you create project schedule that does not take into account resource limitations it will not be feasible. So your schedule shall show your resource requirements but take into consideration your resource restrictions.
Regards,
Vladimir

Negative Schedule Variance.

First we need to establish what is the schedule. I would assume in this case it would be a logical linked resource based network. Once you have completed it you will have a Early & Late Curve (Planned Value).

Then Based on your resource availability you will start tracking progress you should be in the envelope. (If you are not you have a problem with the logic or you will be finishing the project early or late.

So if your planned value is no good and your schedule Variance is Negative yes it is possible to be ahead of schedule.

But remember the Q has to do with behind schedule and does not say you will complete late. You can be late / or Early on non Critical items which have no impact on your CP.

But once you fall behind your late Value you have impacted your CP and you will complete late if you do not accelerate or do corrective actions. But Normally I would put input my forecast which will reflect when you will be completing.

Yes Vlad I have read the presentation but I use a total different approach to planning than you. I don’t believe in using resources as a constraint. I believed the schedule will tell us the amount of resources required rather than allowing the resources to tell us what schedule they can achieve. (That is how I understand the presentation) Please correct me if I am wrong.

Jaco,
read the presentation and then let’s discuss.
You can assume anything if you don’t know the arguments of your discussion partners.
Regards,
Vladimir

Hi Jaco,
Want an example?
I had made a presentation at the Performance Management Congress in Australia where this problem was discussed. If you are interested download it from http://www.spiderproject.ru/library/SDPM_Canberra2004.pdf

Best Regards,
Vladimir

If SV is negative it means that you have done a work that has planned cost less than a work that was planned to be done to the moment. It does not mean that you are ahead or behind the schedule.