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Why do Start/Finish dates automatically change to match Actual Start/Finish dates? RRS feed

  • Question

  • Please excuse my ignorance, but what is the rationale for MS Project automatically changing the "Start" and "Finish" dates to match the "Actual Start" and "Actual Finish" dates when they are inputted?  Can this "feature" be disabled?

    Thanks in advance for any assistance.

     

    Tuesday, June 7, 2011 3:45 PM

Answers

  • Start/Finish represent your current estimated Start/Finish dates based on
    what you know as of this moment.  If the task has completed, then it stands
    to reason that you know what the Start/Finish dates are.
     
    If you'd like to take a snapshot of your project before execution, you need
    to take a baseline and then use the Baseline Start/Finish fields for comparison
    with your schedule.  Then your schedule will tell you, based on what you
    know now, how much of a variance you're predicted to have.
     
     

    Andrew Lavinsky [MVP] Blog: http://azlav.umtblog.com Twitter: @alavinsky
    • Marked as answer by emerald77 Tuesday, June 7, 2011 5:49 PM
    Tuesday, June 7, 2011 4:41 PM
    Moderator
  • Hi,

    Here's the rationale.

    Say Task A is scheduled to end Tue May 3, and it has a predecessor linked Finish to Start to Task B which thus starts Wed May 4.

    Now bad news, Task A only finished May 10. Then obviously Task B can only start on May 11 - from a Finish to Start link... which implies that A's finish is May 10. In fact, from a scheduling point of view, the date of May 3 has become completely meaningless. You can keep it for comparison purposes, hence the baseline: see Andrew's post.

    Thus no, this cannot be disabled, it is essential to the scheduling logic.

    • Marked as answer by emerald77 Tuesday, June 7, 2011 5:48 PM
    Tuesday, June 7, 2011 4:46 PM
    Moderator

All replies

  • Start/Finish represent your current estimated Start/Finish dates based on
    what you know as of this moment.  If the task has completed, then it stands
    to reason that you know what the Start/Finish dates are.
     
    If you'd like to take a snapshot of your project before execution, you need
    to take a baseline and then use the Baseline Start/Finish fields for comparison
    with your schedule.  Then your schedule will tell you, based on what you
    know now, how much of a variance you're predicted to have.
     
     

    Andrew Lavinsky [MVP] Blog: http://azlav.umtblog.com Twitter: @alavinsky
    • Marked as answer by emerald77 Tuesday, June 7, 2011 5:49 PM
    Tuesday, June 7, 2011 4:41 PM
    Moderator
  • Hi,

    Here's the rationale.

    Say Task A is scheduled to end Tue May 3, and it has a predecessor linked Finish to Start to Task B which thus starts Wed May 4.

    Now bad news, Task A only finished May 10. Then obviously Task B can only start on May 11 - from a Finish to Start link... which implies that A's finish is May 10. In fact, from a scheduling point of view, the date of May 3 has become completely meaningless. You can keep it for comparison purposes, hence the baseline: see Andrew's post.

    Thus no, this cannot be disabled, it is essential to the scheduling logic.

    • Marked as answer by emerald77 Tuesday, June 7, 2011 5:48 PM
    Tuesday, June 7, 2011 4:46 PM
    Moderator
  • Andrew - Thanks for your response.
    Tuesday, June 7, 2011 5:37 PM
  • Hi Jan - Thanks for your response.  Your example really put the rationale into perspective.

     

    Tuesday, June 7, 2011 5:48 PM
  • Hi Jan,

    I'm new here and I've just started using MSP 2013 and ran into this same problem/question. While I understand the rational, what confuses me and I hope you can answer is, why have multiple columns with different labels performing the same function?

    I found this happens with the "Scheduled Start" date too. "Scheduled Start" would lead you to believe this is your initial planned start date which remains static and "Actual Start" would be, well, the Actual Start date. So one value by definition would be different than the other, yet when any "Scheduled Start", "Actual Start", or "Start" are changed, they all change to the very same value, why? Is there a scheduling technique or purpose for this to work this way?


    Tuesday, February 17, 2015 4:25 PM
  • Hi,

    In the end, yes, once actuals are recorded, all these values are the same - but before that they can all be different!

    Before an actual start is recorded, the column shows "NA" (wich obviously is different from Start :-)). To the scjheduling engine, thsi means the start can be freely calculated (from predecessors or resource leveling, f.i.) whereas when a date appears in Actual Start, Project will take that value as carved in granite - it is supposed to show past reality, and reality is more powerful than values calculated by the scheduling engine!

    So these two values are not Always identical!

    As for Scheduled start, that is indeed meaningless for automaticlly calculated tassk. But for manually scheduled tasks it does play a role. For a manually schduled task, you can set any start value you want (even a litteral such as "when we have the time"). Still, there is an option to make manually scheduled tasks obey links - the result of that calculation is then put into scheduled start - and so there can be a difference between these two columns as well.

    So, no, these 4 values do not have the same function. They are ony identical as soon as actuals are recorded but what do you expect? There is only one past reality, Project does not work with a parallel universum :-)

    Hope this helps,

    Tuesday, February 17, 2015 6:41 PM
    Moderator