predecessor if statements


I am working with a project plan in excel. I want to write an if statement in my predecessor column that says if there is not a actual finish date than this task cannot be started. I have an estimated start and finish and an actual start and finish. I also have estimated duration and actual duration. I have if statements in these fields already that allow me to plug in duration days and it will auto populate my dates. I am having a very hard time here can someone help me?



Agreed with Variatus, your question is not well stated. When in doubt, include a sample file.
don (rep: 1960) Apr 26, '17 at 12:24 pm
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It's hard to tell what you need but I guess it is a nested IF statement in a column that defines the beginning of a project's time calculation. Something like

= IF([PredecessorEndDate], IF([Duration], [PredecessorEndDate] + 1, 0), "Can't start")

In plain words, If there is an end date for the predecessor, check the Duration and set the start date (where the formula is located) to the predecessor's end date plus 1 day. Else, if there is no end date, write "Can't start".

The peculiarities here twice used is that (a) Excel evaluates any number to True and zero to False, and that a date is a number (if properly entered). Therefore, IF([PredecessorEndDate] and IF([Duration] would both be False if the referenced cells are empty, meaning that the project could also not start if no duration has been set for it. This condition would result in a zero entered as [StartDate]. You could use "" instead, but I prefer 0 because Excel is about numbers. You can format the cell to hide the zero and show a blank or even to display "Enter duration" when the value is zero, while other formulas referring to the start date could be made to take their lead from the zero value with similar IF conditions.

I hope this helps a little.


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