Calculating progress on parent tasks according to overall percentage complete

This topic describes in detail how the progress marking on expanded tasks, summary tasks and hammocks is calculated when you choose to calculate progress on parent tasks according to overall percentage complete (specified using the Progress method field that appears both on the Progress tab of the Options dialog and on the Properties tab of the Properties dialog).

Each task is automatically assigned an 'overall percent weighting' value, which indicates the relative importance of the task in determining the progress of its parent task. The weighting of each task is initially set to be the original duration of the task in hours. For example, a task with an original duration of 7h will have a weighting of 7; a task with an original duration of 75h will have a weighting of 75; and so on. Milestones are the exception: they are assigned a weighting of 1. Milestones are excluded from the calculations, unless they appear in a chart or summary group that contains only milestones (see below). The weighting value of a task changes to match the task's duration until progress is recorded against the task, at which point the weighting is fixed.

You can view the weighting of each task by displaying the 'Overall percent weighting' field in the spreadsheet:

The Overall percent weighting field displayed in a spreadsheet column

In the above example, the 'Start' milestone, and three of the four tasks in the 'Preparation' summary group have some progress; the two milestones have an overall percent weighting of 1, and each task has a weighting that is equal to their duration in hours:

Task Duration in Hours Overall Percent Complete Overall Percent Weighting
Start 0.00 100.00 1.00
Research 7.50 100.00 7.50
Analysis 15.00 100.00 15.00
Proposal 37.50 50.00 37.50
Design 75.00 0.00 75.00
Finish 0.00 0.00 1.00

The overall percent complete of parent tasks is calculated as follows:

  1. The overall percent complete of each task (excluding milestones) in the chart or summary group is multiplied by its overall percent weighting.
  2. The resulting amounts are summed.
  3. The resulting amount is divided by the sum of the overall percent weighting values of the tasks (excluding milestones) in the chart or summary group.

In this example, this gives us the following calculation:

((100.00 x 7.50) + (100.00 x 15.00) + (50.00 x 37.50) + (0.00 x 75.00) / (7.50 + 15.00 + 37.50 + 75.00) = 30.56

Adjusting the overall percent weighting of tasks

You can adjust the overall percent weighting of tasks. Reduce the weighting to indicate that the task should contribute less towards the overall percent complete of its parent task, or increase it to indicate that the task should contribute more. A task with a weighting of 20.00 has twice the effect of a task with a weighting of 10.00, which in turn has twice the effect of a task with a weighting of 5.00. Once you have adjusted the overall percent weighting of a task, it does not change, even if the duration of the task changes.

In the example above, if you changed the overall percent weighting of the 'Analysis' task from 15.00 to 30.00, its contribution towards the overall percent complete of the parent task would be doubled; and if you changed the overall percent weighting of the 'Proposal' task to 20.00, its contribution would be roughly halved. The 'Preparation' summary task would then have an overall percent complete value of 35.85:

The same summary group, with changed overall percent weightings

This is calculated as follows:

((100.00 x 7.50) + (100.00 x 30.00) + (50.00 x 20.00) + (0.00 x 75.00) / (7.50 + 30.00 + 20.00 + 75.00) = 35.85

To change the overall percentage complete weighting of a task, either:

  • Display the 'Overall percent weighting' field in the spreadsheet and edit its value.
  • Edit the Overall % complete weight field in the Progress section of the Task tab of the Bar and Task Properties dialog. '1.00' appears by default in this field. This means that Powerproject will calculate the overall percent weighting of the task automatically, setting it to be the task's original duration in hours. If you change this value, the value you have entered then appears in the Calculated weight field, and does not change, even if the duration of the task changes.

If you have not manually edited the weighting - if '1.00' appears in the Overall % complete weight field - the calculated weight changes to match a task's duration as the duration changes, until progress is recorded against the task; at this point, the calculated weight is fixed - unless you subsequently edit it manually.

If you have manually edited the weighting of a task and subsequently want to revert to its weighting being calculated automatically, you can enter '1.00' in the Overall % complete weight field. The weighting will then be calculated automatically once more, according to its original duration in hours.

If you have changed the overall percent weighting of one or more tasks in a chart or summary group and you want to reset them back to their original values - ie, to make the weighting of each task equal to its duration in hours - right-click the expanded task or summary task in the bar chart, or right-click a chart or summary group in the project view, and select Calculate task weightings.

The overall percentage complete weighting of parent tasks affects the progress of other parent tasks to which they themselves are subordinate. You can configure Powerproject to calculate the weighting of parent tasks automatically, or to allow you to edit the weighting of parent tasks manually. You do this using the Use calculated overall % weights check box on the Properties tab of the Properties dialog: select the check box to calculate the weighting of parent tasks automatically, or clear the check box to allow you to edit the weighting of parent tasks manually.

Subcharts and summary groups that contain only milestones

If a subchart or summary group contains only milestones, the above does not apply; in this case, the completion state of the milestones alone is used to calculate the rolled up progress of the parent task. For example, if a summary group contains four milestones of which three are 100% complete, the summary task will have an overall percentage complete progress figure of 75%.

The overall percent complete of parent tasks in subcharts and summary groups that contain only milestones is calculated as follows:

  1. The overall percent complete weightings of all completed milestones are summed.
  2. The resulting amount is divided by the sum of the overall percent weighting values of the milestones in the chart or summary group.

In this example, this gives us the following calculation:

(1.00 + 1.00 + 1.00 + 0.00) / 4 = 75.00

Four milestones in a summary group; three are completed

If you change the weighting of a milestone in a milestone-only chart or summary group, this affects the overall percent complete of the parent task. For example, if you changed the weighting of the 'Research' milestone in the above example to 2.00, its effect on the overall percent complete of the 'Preparation' summary task is doubled, resulting in an overall percent complete value of 80.00:

The same summary group, with the weighting of one milestone doubled

This is calculated as follows:

(2.00 + 1.00 + 1.00 + 0.00) / 5 = 80.00

Calculating progress on parent tasks as a distributed average

The Overall percent complete, Percent complete and Planned percent complete (PPC) fields normally display values for expanded and summary tasks that indicate the percentage of progress that has been completed without taking into account how the progress is distributed throughout the subchart or summary group.

You can instead choose to display distributed average values, that take into account how the progress is distributed within the subchart or summary group. These values match precisely the shading on expanded and summary tasks.

To display values as a distributed average, select the Show distributed average for charts/summaries check box that appears on the Column Definitions tab of the Table Definition Properties dialog when the Overall percent complete, Percent complete or Planned percent complete (PPC) field is selected.

Related Topics:

Calculating progress on parent tasks according to duration complete

Calculating progress on parent tasks according to effort complete

Calculating progress on parent tasks according to cost complete