Inaccuracies in rolling up task durations of less than a day

Alex G. shared this question 11 months ago
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I have just noticed that you can get some strange results when rolling up task durations in minutes which are less than a work day.

If these tasks all fall on the same day the totals are wildly inaccurate - in one example, four 10-minute tasks were rounded up to 4 hours 10 minutes (see first example below). In addition, if there are some tasks on one day and others on the following day the first day in the rollup is counted as a whole day - to use the previous example, if one of the tasks is shifted to the next day the rollup becomes 1 day and 10 minutes (see second example below).

Incidentally, the effort if used provides an accurate total, and the addition or removal of relationships makes no difference.

The obvious workaround is to add a formula to the central topic to sum the subtask durations in minutes or hours, but this is a bit odd. I can understand the second issue - sort of - as this represents the overall project duration from start to finish, but it's still misleading and why the total duration should be inaccurate for tasks occurring on the same day I have no idea.

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Replies (1)

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Hello Alex


The rolled-up duration is the time from the beginning of the first task to the end of the last, rather than the sum of the durations. For example, if the tasks are scheduled simultaneously then the rolled-up duration would be smaller than the sum. Are you sure you don't have slack time in the schedule? I can reproduce something similar by scheduling 1-hour tasks then reducing their duration to ten minutes. The overall duration does not reduce.

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Hi Nick,

I suspect that may be the cause of the problem.

It’s a little problematic scheduling very short duration tasks in MindManager as it’s hard to apply a start time. In fact I did create the tasks with longer durations and then cut them down, which means that the starting times may have remained the same.

This would also explain the situation with multi-day tasks. Regardless of the length of the tasks involved, the duration is calculated as running from the start of the first task on the first day to the end of the last task on the final day.

The upshot is that if you want to sum the actual duration of all the individual tasks you have to use a formula on the central topic to total the duration task attributes of all the children tasks.

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