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# What does the following mean when doing schedule analysis

3 replies [Last post]
Raul Santos
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Joined: 29 Oct 2009
Posts: 44
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What does it mean when you run a Varance Report (comparing end dates between the baseline schedule against the current schedule) and you have negative variance for some activities and also TF = 0 for those same activities? These activities have slipped to the right (delayed), but still meet the schedule end date. How can this happen? Can you please explain what might be happening? Thanks in advance for your responses.

## Replies

Jorge Payne
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Joined: 3 Feb 2012
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It could also be that the network logic is incomplete.  If you have a series of activities forming a path that is not somehow anchored at the end, either by the project completion or by a constraint (Finish No Later Than), and your analysis is not based on longest path, then the total float for that path will always be zero.  This is due to the backward pass originating at the end of that path, the same point that the forward pass ends, so the lates will always equal the earlies and total float =0.  But that is only one possible explanation.

Rafael Davila
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Joined: 1 Mar 2004
Posts: 5091

If you compare Early vs Early or Late versus Late you will record slippage but not float consumption. Use Baseline Late Dates minus Current Early Dates for float consumption, a simple formula or Global Change shall do it. An alternate way is to compare float values between Baseline and Current.

If your current job is ahead of schedule your float consumption shall be negative (depending on your comparison settings Baseline minus Current or Current minus Baseline), you have created float available for your benefit and for those who want to take it away from you.... LOL

Regards,

Rafael

Daniel Limson
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Joined: 13 Oct 2001
Posts: 318
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Hi Raul,

Granting the the programme logic is correct, the Variance Report should tell you what activities have slipped against your baseline programme and how much time (total float) you still have before impacting the project completion date. If you are saying that you have now TF=0, it simply means that these activities are now critical and should be completed on time otherwise these activities are already delaying the project completion. I would suggest to filter all these activities and discuss it with the construction team  so that mitigation measures or work around can be plan ahead to avoid delaying the proejct completion.

Best regards,

Daniel