Calculating progress on parent tasks according to effort 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 the amount of effort that has been completed (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).

When progress on parent tasks is calculated according to effort complete, only the effort on scheduled permanent resource allocations is taken into account; the effort on demand permanent resource allocations is excluded from the calculations. Both allocations on the tasks contained within a parent task and allocations on the parent task itself are included in the calculations.

Note that while the contents of hammock tasks are excluded from the calculations, any allocations that are made directly onto a hammock task affect the progress date of the hammock task itself - although this is not rolled up any further to parent tasks at a higher level.

Powerproject calculates progress on parent tasks according to effort complete in a similar way to that in which it calculates progress according to duration complete. It creates a 'profile' of values against time, but this time to represent the distribution of effort.

Consider the following scenario, in which a summary contains three tasks. Two of the contained tasks and the summary itself have one or more scheduled resource allocations. Note that each working day is 8 hours long in this example:

A summary containing three tasks; two of the contained tasks and the summary itself have one or more scheduled resource allocations

Powerproject creates a 'profile' of effort against time, to represent the distribution of effort. Here is a description of the allocations in order, from the top down, with a description of how much effort each one contributes towards the profile:

  • The first allocation (effort 48h; duration 16h) contributes 3 seconds of effort per second in the profile (48h / 16h = 3 hours per hour, or 3 seconds per second).
  • The second allocation (effort 8h; duration 8h) contributes 1 second of effort per second in the profile (8h / 8h = 1 hour per hour, or 1 second per second).
  • The third allocation (effort 16h; duration 8h) contributes 2 seconds of effort per second in the profile (16h / 8h = 2 hours per hour, or 2 seconds per second).
  • The fourth allocation (effort 20h; duration 20h) contributes 1 second of effort per second in the profile (20h / 20h = 1 hour per hour, or 1 second per second).

The resulting profile is illustrated below (note that Powerproject never actually displays such a profile for viewing; it is purely used internally for carrying out progress calculations):

The resulting profile

The total amount of completed units contributed by the allocations is as follows:

  • The first allocation (effort 48h; 50% complete) contributes 24 hours (86,400 seconds) of completed units.
  • The second allocation (effort 8h; 0% complete) contributes no units.
  • The third allocation (effort 16h; 0% complete) contributes no units.
  • The fourth allocation (effort 20h; 40% complete) contributes 8 hours (28,800 seconds) of completed units.

The total amount of completed units in this example is therefore 115,200 seconds. The progress date for the top-level summary task is calculated by finding the date at which the cumulative area underneath the graph equals 115,200 seconds.

The areas of the sections in the above profile (from left to right) are as follows:

  • Section 1: 3 x 14,400 = 43,200 (14,400 being the number of seconds in a half day in this example).
  • Section 2: 2 x 14,400 = 28,800; sections 3, 4, 5 and 6 are identical.

As the cumulative value to the end of the third section is 100,800 and the cumulative value to the end of the fourth section is 129,600, the progress date (equivalent to 115,200) lies somewhere within the fourth section. A simple ratio shows that the date lies towards the start of the section - early on Tuesday morning.

Mixed calendars and durations measured in elapsed time

The procedure for calculating the progress of parent tasks according to effort complete when tasks use different calendars is identical to that described above.

When a task's duration is marked in elapsed time, it is assumed that work takes place continuously on the task for 24 hours per day and the task's calendar is ignored.

Nested hammock tasks

As mentioned previously, allocations made to nested hammock tasks and their contents do not contribute towards the progress of any summary or expanded tasks in which they are contained. This is because it is assumed that the contained allocations will be taken account of elsewhere in the project.

Milestones

For the purpose of calculating progress on parent tasks, milestone allocations are given a nominal duration of one second.

Calculating progress on parent tasks according to the Effort - Approximate method

If you are working with a very large project, you may find that calculating the progress on parent tasks takes a considerable time. You can reduce the amount of time that it takes by selecting the Effort - Approximate method of progress calculation in the Progress method field that appears both on the Progress tab of the Options dialog and on the Properties tab of the Properties dialog.

This method works in a similar manner to that outlined above, but the effect of calendars is ignored in large projects, which simplifies the calculations. Normally, the contribution of a single allocation to the effort distribution is a value of 1.0 during working time and 0 during non-working time; if the Effort - Approximate method is used, a single value is used throughout an allocation's duration.

The value that is used depends on the ratio of working time to non-working time, so that the area under the profile for an allocation is the same as it would be if the profile dropped down to 0 during non-working time. So if an allocation started at 09:00 on Monday morning and finished at 17:30 the following day (assuming 7.5 hours of working time per day), there would be 15 hours of working time in the allocation's duration and 16.5 hours of non working time. Therefore a constant value of 15 / (15 + 16.5) = 0.476 would be used throughout the allocation's duration.

Related Topics:

Calculating progress on parent tasks according to duration complete

Calculating progress on parent tasks according to cost complete

Calculating progress on parent tasks according to overall percentage complete