Resource Work Not Calculated Correctly with Very Small Units

Q113488

kbusage
The information in this article applies to:

SYMPTOMS

In Microsoft Project, when you use very small units to indicate resource work, the work may be calculated incorrectly, the scheduled finish date may change, and you may receive an alert message that the resource is assigned outside of the dates for the task.


CAUSE

Microsoft Project stores all work, time, and duration in minutes. However, Microsoft Project sometimes has difficulty performing calculations at this level of precision.

Example

In Microsoft Project the default preferences for duration is the following:
1 day task = 480 minutes
If you assign .02 units of a resource to a fixed 1 day task, Microsoft Project calculates 9.6 minutes, or approximately 10 minutes of work. Microsoft Project rounds the 9.6 minutes to the nearest minute which equals 10 minutes.

To compute the duration of the resource so that the finish date of the resource can be calculated, Microsoft Project uses the following formula:
duration = work/units
If you use the numbers from the above example in this equation, you get 10 minutes/.02 units, or 500 minutes; the resource needs 500 minutes to accomplish its total work of 10 minutes. But since the task is fixed at 480 minutes, the error message is generated because the resource needs to work 20 minutes later than the finish of the task.


MORE INFORMATION

Resource work for a fixed-duration task should be calculated based on the following formula

duration x units
and the scheduled finish date for the resource should not change.

Steps to Reproduce Behavior in version 3.0

  1. From the View menu, select Task Entry.


  2. Press your F6 function key to select the lower pane. From the Format menu, choose Resource Schedule. Press F6 to re-select the upper pane.


  3. Create a 1d fixed-duration task.


  4. Assign a resource, let the units default to 1 (Microsoft Project calculates 1d of work).


  5. Change the resource units to .02. (Microsoft Project calculates .02d of work.)


Note that the scheduled finish date of the resource changes to the next day at 8:20 AM and Microsoft Project alerts you that the resource is assigned outside of the dates for the task.

The problem continues until you change both the units back to 1 and the duration back to 8h.

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Last Reviewed: November 3, 2000
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