We recently received a submission that asked how you calculate the percentage of critical activities in the schedule when using P6 Professional? Let’s take a look.
Our P6 inquirer, has a client that wanted to know the percentage of critical activities in their schedule. Percent of Critical activities is one measure of a quality schedule. A schedule with say, less than 5%, critical activities, may have missing logic. And if it has more than 15% critical activities, this could indicate an aggressive schedule. Calculating this percentage value is possible directly using P6 Professional.
This article provides a quick guide through the process of computing the percentage of critical activities in a P6 Professional schedule.
To calculate the percentage of critical activities in the schedule, do the following:
- Create two user defined fields (UDF) of Data Type number. Name them Count and Critical Count. Count is the number of tasks in the schedule and Critical Count is the number of critical activities in the schedule. See Figure 1.
- Choose Tools | Global Change and create the global change routine, called Critical Activities, to assign all critical tasks the value 1.0, Figure 2.
- Choose Tools | Global Change and create the global change routine, called Count, to assign all non-LOE and non-WBS Summary tasks to Count, Figure 3.
- Note in the above Count global change routine, Figure 3, that the matching criteria for each ‘If statement’ is ‘Any of the following’ which includes the Or conjunction after each line of code.
- Run the Critical Activities global change routine, Figure 4.
- Review the Critical Activities global change report and commit changes, Figure 5.
- Run the Count global change routine, Figure 6.
- Review the Count Global Change report and commit changes, Figure 7.
- Confirm that Show Group Totals is toggled on in the Group and Sort dialogue, Figure 8.
- Add the columns Critical, Critical Count, and Count to the activity table, Figure 9.
- Confirm that the Critical and Critical Count columns match for each critical activity.
- Note the group totals numbers at the top of the Critical Count (9) and Count (17) columns.
- In this schedule 52.9% of the tasks are critical.
You are done!
Summary
Schedule quality equates to a healthy and realistic schedule. A schedule that has few critical activities may have insufficient detail or, perhaps, missing logic. And a schedule with many critical activities may not be achievable; it is too aggressive.
Therefore, it is important to find the percentage of critical activities in the schedule.
This is done in P6 Professional using UDFs and the global change routine. Create and then run the critical activity and count global change routines separately, then display their columns in the activity table to capture the total number of critical activities and number of tasks in the schedule. Compute the percentage of critical activities from these values. Schedules with either too low or high a percentage of critical tasks are flagged for review. In this way the scheduler focuses on the schedules whose critical path requires attention to confirm transparency and/or rationale.