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Difference between free slack and total slack

    Domanda

  • Hi

    I am using MSP professional 2010. I have a doubt in it how can differentiate free slack and total slack.

    While scheduling the project total slack is always same as the free slack in Activity. And always 0 at summary task level

    giovedì 28 giugno 2012 05:04

Risposte

  • Free Slack is the number of days that an activity can have before it starts delaying the next (successor) activity.
    Total Slack is the number of days that activity can have before it starts delaying the whole project.

    If you look at the snapshot below ID 4 have Total Slack of 4 days but no Free Slack (as it doesn't have any intermediate Successor other then the last task of the Project which is driving the Project Finish Date) but Total Slack of 4days.

    Total Slack of 4d is showing that it has buffer of 4 days before it finally delay the over-all project finish date.




    Sapna S


    giovedì 28 giugno 2012 09:14
    Moderatore

Tutte le risposte

  • Free Slack is the number of days that an activity can have before it starts delaying the next (successor) activity.
    Total Slack is the number of days that activity can have before it starts delaying the whole project.

    If you look at the snapshot below ID 4 have Total Slack of 4 days but no Free Slack (as it doesn't have any intermediate Successor other then the last task of the Project which is driving the Project Finish Date) but Total Slack of 4days.

    Total Slack of 4d is showing that it has buffer of 4 days before it finally delay the over-all project finish date.




    Sapna S


    giovedì 28 giugno 2012 09:14
    Moderatore
  • Thanks Sapna
    mercoledì 4 luglio 2012 11:04
  • Hi Sapna

    Thanks for the explanation. Are you saying all the other activities in the project (apart from 4 days one) will have delay on the whole project as they have 0 Total slack time? Can you please reconfirm my understanding on same?

    Thanks a lot in advance

    Manish

    venerdì 10 ottobre 2014 03:40
  • Yes your got it, all tasks which have Total slack of 0 falls on critical path and they do impact the project finish date. You can also refer to below links :

    http://office.microsoft.com/en-in/project-help/total-slack-task-field-HP045305403.aspx

    http://epmxperts.wordpress.com/2014/05/03/second-level-critical-tasks-tasks-which-are-near-critical/


    Sapna Shukla

    venerdì 10 ottobre 2014 10:38
    Moderatore
  • re: Free and total slack difference

    The standard definition works when Total slack is equal to or greater than Free slack.  What is happening when Total slack is LESS than Free slack? 

    Joe Wharton, PMP, MCTS.

    martedì 7 marzo 2017 17:45
  • Joe,

    Can you give an example where this would be the case?

    John

    martedì 7 marzo 2017 17:54
  • In Project, Total Slack (of a task) can be less than Free Slack (of the task) only when Total Slack is negative.  What is happening in that case is that one or more applied constraints (including Deadlines and manually-scheduled tasks) are in conflict with the applied logic, such that the late dates precede the early dates.  Keep in mind that Free Slack is computed based on early dates only; it can never be less than zero.

    Constraints, multiple calendars, and resource leveling all interfere with the traditional interpretations of Slack, and one should take care not to over-rely on them.  

     
    martedì 7 marzo 2017 23:25