Deltek Acumen 8.8 Online Help

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Risk-Adjusted Schedule

You can generate scenarios based on risk inputs and outputs.

Understanding the Risk-Adjusted Scenario

When you see a P80 finish date on the Risk Exposure chart, you might wonder why you don't see that date in the P80 risk-adjusted schedule scenario.

The P80 scenario uses the P80 duration for every activity in the schedule and then calculates the critical path. The P80 date on the Risk Exposure histogram simply means that "80% of the Risk iterations finish on or before this date." The P80 date is not one single schedule; it is just a "line in the sand" date. There is no logical way to back a schedule into this date. If you run 1,000 iterations, there are 800 schedules that finish on or before that date, each with different risk-adjusted durations for activities.

By using the P80 duration for each task when building a risk-adjusted schedule scenario, we are assuming the 80% case for each single activity. When running CPM, this generally comes close to the P80 date on the Risk Exposure Histogram, but there is no way to guarantee that the Risk Adjusted Scenario date will match the probabilistic P80 date. This is normal and expected.

Scenarios Based on Risk Inputs

Creating scenarios based on risk inputs is useful when you need to re-calibrate a schedule based on the project's team uncertainty rankings. You can achieve this using one of the following modes:
  • The PERT Method uses the PERT algorithm ((max+4*most likely+min)/6 to re-calibrate the schedule/cost model.
  • The Distribution Median uses the median value between min, most likely, and max to re-calibrate the schedule/cost model.

Scenarios Based on Risk Outputs

You can create a scenario based on any P-Value from the risk analysis. After creating the scenario, you can publish the risk-adjusted schedule back to the scheduling tool or use it as the basis for building a new risk model.

When creating the risk-adjusted scenario, Acumen copies the following selected P-Value data:

  • Remaining Duration is set to the Pxx duration
  • Early Start is set to the Pxx Start
  • Early Finish is set to the Pxx Finish
  • Late Start is set to the Pxx Start
  • Late Finish is set to the Pxx Finish
  • Total Float is set to the Pxx Float
  • Free Float is set to 0 (zero)

Acumen will automatically run CPM if you have selected Run CPM Automatically on the S3 // Risk tab (Analysis > Build Scenario > Run CPM Automatically). This changes the dates copied into the scenario from risk. If you want to retain the dates copied from risk, turn this option off.

Acumen CPM will use the same settings as the project from which you created the scenario. If you want to change them for the scenario, you can do so.

Use the fields on the S3 // Risk Activity Pane Settings tab (when the project is selected in the Gantt chart) to specify how you want Acumen to perform the CPM. For example: You have two activities, Activity A and Activity B. There is a finish-to-start link between them which means that Activity B can't start before Activity A is finished. For some reason, Activity B has started before Activity A has finished, that is, Activity B is now out of sequence.

  • If you select a Retain Logic scheduling mode, Activity B cannot finish until Activity A is finished. The system schedules the remaining duration of Activity B to begin after Activity A is finished. That is, Activity B is put on hold until Activity A is finished.
  • If you select a Progress Override scheduling mode, the system ignores the start-to-finish link between Activity A and Activity B and the activities finish in no particular order.
  • If you select an Actual Dates scheduling mode, the system sets the late finish date of Activity A to one day before the actual start of Activity B which creates negative float.

Risk-Adjusted Scenarios with Weather

Risk windows and calendar events have an option to prevent activities from splitting across the event /window. This can delay the start of the activities mapped to these risks. When you create a risk-adjusted scenario, you set the dates and remaining duration. You do not set a target start (constraint) on the start of activities that were delayed by these events. If Acumen runs CPM on the scenario, or the scenario is exported to a scheduling tool that runs CPM on it, the dates will change.