Dear Gents,
Could anyone assist me in understanding way late start/finish dates would change in a progress-only update.
I assumed that they would remain constant so long as the logic remained intact. However there seems to be some impact from progress/out of sequence.
What are the main causes of late-date changes through progress only updates?
Thanks
Alan
Alan,
In that case it is probably down to OOS working.
Cheers,
G
Thanks Gary,
Actually I probably should have made it a little clearer. I'm trying to understand why the late dates would change without any changes to logic, calenders etc. Just changes to the duration % / remaining duration and data date.
Also I should have mentioned that the project comlpletion is fixed with a 'finish on' constraint, which drives the float negative due to delays.
On that basis the late dates should remain more constant, but I still see changes from update to update.
Hope that's a bit clearer!
Thanks
Alan
Alan,
There are a whole host of reasons why late dates could change during an update (changes to calendars, constraints, OOS working ,etc), but at the most basic level:
Late dates are calculated using the "backwards pass method"
The starting point for this backwards pass calculation is the project completion date calculated during the "forward pass"
The "forward pass" calculation (which calculates your early dates) will be affected by progress-only updates
Or to put it another way: if after updating progress, your project completion is 5 days later than previously, each of your incomplete activities can now finish 5 days later than previously without further delaying the project (which is the definiton of late finish)
You mention OOS, so without going into too much detail: If you have OOS, your early, dates, late dates and hence total float calculations are all suspect.
How and why this is so is a bit complex and depends on your scheduling options -retained logic, progress overide, etc (I go expand on this explanantion if required), but the simple fix is to go back and correct your historical logic links to reflect what actually happened. This will clear your OOS errors and get you back on the straight and narrow wrt early & late dates.
Cheers,
G