Project Summary task

[roberta]

I have inserted via the 0ptions menu a project summary
task and I have now started tracking my project. I have
completed 100% the first three tasks which total 8 days
(al of which started on time and were completed in the
baseline duration times. The associated summary says 8
days but my project summary only shows 5.36 days?

There are no overlaps, calendar constraints, contouring or
anything involved.

Can anyone explain, please, how this is being calculated?

 

[John]

Can anyone explain, please, how this is being calculated?

Roberta,
Duration for summary tasks is simply the number of working days between
the subtask under it with the earliest Start date and the subtask with
the latest Finish date. This is also true of the Project Summary Task.

However, it sounds like you are actually looking at the Actual Duration
field. For a summary task this value is calculated as the ratio of the
sum of subtask Actual Durations to the subtask total Durations times the
Duration of the summary task. For example, assume a summary task with a
total Duration of 62 days has three subtasks. The first has 62 days
duration and is 100% complete. The second has 20 days and is 100%
complete. The third has 20 days and is 50% complete. The sum of Actual
Durations for the 3 subtasks is:
100% * 62 + 100% * 20 + 50% * 20 = 92 days
The total Duration of all three subtasks is 102 days. The ratio is
therefore 92/102 = 90.1%. Multiplying this by the total Duration of the
summary gives and Actual Duration for the summary task as:
90.1% * 62 = 55.92 days.

Hope this clarifies things.
John