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Task Type and Resource Effort RRS feed

  • Question

  • Guys,

    I'm playing around with tasks types in a test Project and I'm struggling to see why Project is doing something.

    Enter a new task "test task", set the Work to 5 hours. Project keeps duration at 7.5? hrs. Add a resource and Project sets it to 67% complete. What I'd like Project to do is set the duration to 5 hours, and not change the effort. This is with a Fixed work or Fixed Units task.

    If I do a Fixed Units and Effort Driven task it seems I can get to what I want. If I create a task as Fixed Units, enter 3 hours, then put a resource it marks it as 40%, if I set the task to Effort Driven it doesn't change the duration to 3 hours as I'd expect.

    Nowhere in the articles I have read does it say that the task type has any impact on the effort percentage a resource can work.

    What I'd like to do is setup a Project for IT development, it would have a bunch of developers with different % that I would set, for example a Lead Dev at 70% and other devs at 90% for example. I'd not want Project to change those percentages. I'd want to enter the hours of work, as dictated to me by the developers and the duration to reflect this. I believe these tasks to be the sort that if I add another developer to a task the duration should be lowered but the work kept the same.

    It seems to me that effort driven fixed units tasks should be my go to task type, however, this article:

    https://support.office.com/en-us/article/Change-the-task-type-Project-uses-to-calculate-task-duration-5a421722-6618-451f-8d3c-0f7c45c1d2d2

    Suggests that if I change the WORK on a FIXED WORK task type that the task's duration should be recalculated. In my case that is not happening, it's revising the resource's effort. I don't understand why.

    Wednesday, May 20, 2015 2:51 PM

All replies

  • To take your post apart question/comment at a time:

    I'm playing around with tasks types in a test Project and I'm struggling to see why Project is doing something. Enter a new task "test task", set the Work to 5 hours. Project keeps duration at 7.5? hrs. 

    A couple of assumptions:  You have changed both your definition of "day" to 7.5 hours as well as changed the working time to 7.5.  When you add a task without entering duration, Project will set the duration to the default of "1 day".  As you have set your duration to show in hours - it shows 7.5 hours.  When you enter work, there is no tie between work and duration unless you have a resource assigned.

    Add a resource and Project sets it to 67% complete. Really?  Or does it calculate 67% for assignment unit?  

    What I'd like Project to do is set the duration to 5 hours, and not change the effort. This is with a Fixed work or Fixed Units task.    Then enter the 5 hours in the duration field.  Assuming your resource is assigned at 100%, the 5 hour duration will calculate 5 hours of work.  The formula is:

    Duration (5 hours) * Assignment units (100%) = Work (5 hours).

    If you enter both Duration and Work - then Project assumes you want to calculate assignment units using the formula below:

    Work (5 hours)/Duration (7.5 hours) = 67%

    The one difference is if you try to enter more work than can be done in the duration set.  For example 50 hours of work for a one day duration.  In that circumstance, Project will recalculate the duration. (assuming you are NOT using Fixed duration).

    If I do a Fixed Units and Effort Driven task it seems I can get to what I want. If I create a task as Fixed Units, enter 3 hours, then put a resource it marks it as 40%, if I set the task to Effort Driven it doesn't change the duration to 3 hours as I'd expect. Effort driven has nothing to do with the assignment of a single resource to a task.  I think you are muddling duration (how long does the task take) and work (how much effort is going to be expended duration the task duration).  Is it 3 hours of work or 3 hours in duration?

    What I'd like to do is setup a Project for IT development, it would have a bunch of developers with different % that I would set, for example a Lead Dev at 70% and other devs at 90% for example. I'd not want Project to change those percentages.

    I'd want to enter the hours of work, as dictated to me by the developers and the duration to reflect this. I believe these tasks to be the sort that if I add another developer to a task the duration should be lowered but the work kept the same.

    Do you want your resources to be assigned at their max units (70%, 90%) ?  If so, create the task (Fixed Units).  When you assign the resource, enter the work for each resource.  Project will calculate the duration.  If you think that the addition of more resource should drop duration and divide the work among the resource, yes, Effort Driven is what you need.

    It seems to me that effort driven fixed units tasks should be my go to task type, however, this article:

    https://support.office.com/en-us/article/Change-the-task-type-Project-uses-to-calculate-task-duration-5a421722-6618-451f-8d3c-0f7c45c1d2d2

    Suggests that if I change the WORK on a FIXED WORK task type that the task's duration should be recalculated. In my case that is not happening, it's revising the resource's effort. I don't understand why.

    Are your tasks automatically or manually scheduled?




    Wednesday, May 20, 2015 4:33 PM
    Moderator
  • Hello Julie,

    Many thanks for taking the time to reply. It's much appreciated, I have two big projects coming up and I want to make sure I get the plans bang on before I start tracking.

    I have indeed changed my definition of a day to 7.5 hours to reflect our working times, I do measure work and duration in hours too - a lot of our projects call for this and it plays well with other systems.

    Sorry, I didn't mean 67% complete, I meant 67% 'effort' - basically whatever fraction of the 7.5hr I entered as work.

    What seems to make a difference is the order of operations. If you create a task, in this case 'fixed units', add the resource, set the work to 2 hrs, it changes duration to 2hrs. If you create the task, set the work, 2hrs, and add the resource, it sets the resource to 27%. So it seems whether you add the work or the resource first has an implication on whether the duration is changed or the resource % is changed. Is this intended behavior, it seems very odd.

    My tasks are all set to automatic.

    I've setup two practice scenarios:

    1. Adding WORK first, 3hs, then resources.

    a.Fixed Units Task

    b.Fixed Units Task, Effort Driven

    c.Fixed Work Task

    In all cases the resources are then set to 40%. If I add a resource to a. it changes the work to 10.5 hrs. If I add a resouece to b. it changes the duration to 2.14 hours. If I add a resource to c. it does the same.

    2. Adding resource first, then hours (3)

    a.Fixed Units Task

    b.Fixed Units Task, Effort Driven

    c.Fixed Work Task

    Resources are set to 100% so duration is 3hr?. In a. duration stays at 3hr, work is 6hr. In b. duration is set to 1.5hr? and work 3hr. In c the same.

    So, my conclusion is that the order of operations is most critical. I must add resources first and then work (which seems strange), and I must choose an effort driven task.

    What is not clear is what the difference is between Fixed Units, Effort Driven and Fixed Work. At the moment they seem to be behaving identically.

    I guess after all this waffle my questions are:

    1. What's the difference between Fixed Units Effort Driven and Fixed Work task types?

    2. Is it correct that the order of operations effects whether the duration or resource% is changed - I'm sure when I wrote project plans a year ago or so this wasn't the case.

    Thanks!


    • Edited by Rob-R Thursday, May 21, 2015 8:33 AM .
    Thursday, May 21, 2015 8:31 AM
  • Hi Rob,

    You're welcome and thanks for the feedback.

    Yes, the order that you enter the data does impact what Project calculates.

    1. If you enter task duration only and then assign a resource, Project will assign the resource at his/her max units (assume 100% or less) and calculate the work for the resource based upon the formula Duration * Assignment units = Work.
    2. If you enter task duration and work and then assign a resource, Project will calculate assignment units based upon the formula Work/Duration = Assignment units.  As I mentioned above, if the work is greater than can be accomplished in the duration, Project will increase duration.
    3. If you enter duration and when you assign the resource you enter the work then Project will assign the resource at his/her max and recalculate duration using the formula: Work/Assignment units = Duration.

    In your first scenario (work entered before assignments) you are seeing what I describe in #2 above.  Project calculates assignment units because you explicitly told it duration and work before assigning the resource.  When you added resources, then what became important was whether the task was effort driven or not.

    • Add a resource to a Fixed Units, non-effort driven task with a resource assigned: Project calculates the work for the added resource based upon Duration * Assignment units.  The first resource had 3 hours of work, the additional resource gets 7.5 hours of work (7.5 hours duration * 100% assignment units).  Total work is 10.5 hours.
    • Add a resource to a Fixed Units, effort driven task with a resource assigned: Project assigns the new resource at his/her max units (100%) and divides the 3 hours of work based upon assignment units.  The first resource (at 40%) gets .85 hours of the 3, the second resource (at 100%) gets 2.15 hours of work.  The duration drops because more resources are performing the 3 hours of work.
    • Add a resource to a Fixed Work task.  Fixed Work tasks are effort driven, so the results are the same as adding a resource to a Fixed Units, Effort driven task.

    My suggestion is to use the Task Form shown in the lower pane (split your screen) to assign resources.  When using the task form you can see/change task type, effort driven settings and see precisely what is being calculated for work and effects on task duration when you assign additional resources.  I also use the Task Form to enter the work for each assignment (resource) when I assign the resource.  This is particularly useful when you have multiple resources assigned to tasks and the work estimates from each resource is different.

    Regarding your question about difference between Fixed Units, Effort Driven and Fixed Work.  If you just add and subtract resources, mostly nothing.  The difference in task types dictate what Project will change if you change one of the other variables.  The Link you gave in your first post explains it nicely.

    Regarding the question of order of entry - yes.  As noted above.

    I hope this helps.




    Thursday, May 21, 2015 1:57 PM
    Moderator
  • Hello Julie,

    Thanks for the comprehensive reply again, sorry my response is a little tardy, we've had a long weekend in the UK and I wasn't in the office.

    I have the task details form visible now and I can see what you mean, it allows for so much more control.

    I'll be careful with the order of entry, as regards task type, if it makes no difference I think I'll stick to Fixed Work.

    Thanks again your responses have been very helpful :)

    Tuesday, May 26, 2015 3:22 PM
  • You're welcome, Rob and thanks for the feedback.

    Just to be clear - task type does make a difference if you start changing one of the variables. For fixed work tasks, if after you have a resource assigned, you change the duration of the task, the assignment units will be recalculated.  If you change the units, the duration is recalculated.

    Tuesday, May 26, 2015 3:51 PM
    Moderator
  • Thanks Julie. I've just had a play...

    Task A - Fixed Work, assign a resource, add work to 3 hours, duration changes to 3 hours.

    Task B - Fixed Units ED, as above.

    If I change the resource to work only 80% of the time the same thing happens in both cases - the duration changes to 5 hours.

    If I change the work to 6 hours in both cases the same thing happens - the duration increases to 6 hours.

    I never change the duration, but for completeness I did, changing it to 8 hours, in both cases work increased to 8 hours.

    I know there must be a difference, however, I'm struggling to find it under this simple example!

    Thanks once again

    Tuesday, May 26, 2015 4:03 PM
  • Yes, in both Fixed Work and Fixed Units tasks, if you change units, duration changes. If you change work in a Fixed Work or Fixed Units task, duration changes.

    But change Duration in both tasks and you will see the difference.  In a Fixed Units task if you change duration, Work will change.  In a Fixed Work task, if you change duration, units changes.

    Again, the original article you noted above (https://support.office.com/en-us/article/Change-the-task-type-Project-uses-to-calculate-task-duration-5a421722-6618-451f-8d3c-0f7c45c1d2d2) has a very nice table at the beginning that shows all variations.

    Tuesday, May 26, 2015 4:54 PM
    Moderator
  • Thanks Julie, practically speaking, duration isn't something I change - I like project to roll it up so I can see when my development will finish.

    Theoretically speaking, with my 1 resource per task setup I didn't see any difference between the three tasks

    • Fixed Work
    • Fixed Units, Effort Driven
    • Fixed Units

    When I changed the duration the work changed. When I repeated the process but assigned two devs per task I saw the difference. Project puts in work as 15 hours and keeps duration at 7.5 hours in all cases. I change work to 25 hours, duration goes up to 12.5 hours in all cases. If I change duration to 15 hours then in the FIXED WORK task work remains at 25 hours, in the other two cases the work increases to 30 hours.

    I have developers giving me an estimate for work - this task will take me 4 hours. If I add 2 developers I want it to reduce to 2 hours. It seems both Fixed Work and Fixed Units Effort Driven will get me to this.

    The difference seems to be if I change the duration, to three hours then the Fixed Work remains at work of 4 hours, the Fixed Units ED changes to 6 hours of work. If I reduce the duration to 1 hour the FW task is over allocated and work stays at 4 hours, the FU ED task changes work to 2 hours.

    This makes me think Fixed Work is the way forwards, so if I do something dumb like change the duration to less than the work Project will kick off and say I've over allocated my resource, rather than tell me 'hey it's less work than the dev told you'!

    Thanks for the replies and patience Julie! - I think I'm set now, I'll use Fixed Work tasks, I'll add the resource(s) first and then the work. I'll not change the duration I suspect.

    Wednesday, May 27, 2015 9:19 AM