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Microsoft Project – Tasks – real time vs assigned time

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  • #516639 Reply

    Hi, I have a small issue with Microsft Project, but unfortunately I do not know, how to deal with it.
    We use Micsrosoft Project 365 for our projects, e.g. obtaining a building permission.
    To some tasks were assigned several days or weeks e.g. preparing some documentation or manager´s signature, but in fact the real work does not last so long (days or weeks). This leads to the fact that the assigned sources are overloaded- Hpw can I deal with this?

    Thank you

    #516653 Reply
    daryl deffler

    Without having detailed tasks to examine, it sounds like confusion between task duration and resource work. It can also get complicated to understand what MS Project is doing behind the scenes. So to start with, MS Project has a formula that it applies to every task and that formula must stay in balance. That formula is:
    Duration = Work / Availability (resource units)
    * Work is the amount of effort a resource will expend to complete a task. For example, obtaining a managers sign off may take .5 hours, or creating a report may take 8 hours of work.
    * Duration is the calendar length of time it will take the resource to complete the work. For example, 3 days to get the managers sign off, or 1 week to complete the report.
    * Availability is resource units. Its the amount of time per period (day/week) a resource is available to perform the work. This comes from the resource calendar which defines working days and hours/day.

    If you assign a resource to a task such as Create Report, and you give that task a duration of 5 days (a week), then MS Project will look at the assigned resource’s availability and reverse calculate how much effort (work) to assign to the resource. Assuming the resource is M-F 8 hours per day, MS Project would calculate the resources work estimate to be 40 hours. If the resource calendar says they are only available 4 hours per day, then MS Project would calculate the work estimate to be 20 hours.
    What you need to understand is that when you change one value in that formula manually (by making changes to the task), MS Project will adjust another value (without telling you) to keep that formula in balance. For example, if you changed duration to 3 days, the work estimate would be changed to 24 hours to keep the formula in balance.

    But there are ways to control that formula and this is done using the task type. Meaning you can lock a specific value of that formula so that Project can’t change it. If you define your task as Fixed Duration, that part of the formula stays locked. For example, if you create a Fixed Duration task of 5 day to create the report, Project will calculate the resource work at 40 hours. If you then change the work estimate to 8 hours, project will adjust the Availability parameter of the formula and the result will be 8 hours of work spread across 5 days duration. Conversely, if you define a task as Fixed Units, you are locking the resource availability component of the formula. In that case, if you defined your Create Report task as 5 days and then changed the resource work estimate to 8 hours, MS Project will change the duration to 1 day because the availability component is locked.

    I know this is a bit more than a simple just-do-this answer, but I wanted to give some background on why Project is doing what it does.

    Normally, I would recommend that any task is defined (as a default) as Fixed Units so that MS Project doesn’t try to change resource availability, but instead uses resource availability and work estimates to determine what the duration should be. Note that Project will change resource units to exceed 100%. By locking availability (units) we avoid this.

    However, in some cases, such as obtaining a Manager Signoff where duration is the driving force for scheduling, I’d recommend defining the task as Fixed Duration (for example 3 days), then adding the resource work estimate and letting Project determine the availability of the resource during that duration to complete the work.

    If you define those problem tasks (as in your example) as Fixed Duration, assign the duration, then assign the resource work estimate, your schedule should be much cleaner.
    Hope that helps.

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