Schedule Risk Analysis With Acumen: Different Calendars

Marty Fuentes
| December 23, 2020

This article provides an overview on how varying inputs and parameters affect the date outputs, in particular, the P0, P50, and P100 dates, in the Schedule Risk Analysis (SRA) with software Deltek Acumen Fuse. By understanding how Acumen behaves with respect to varying conditions, schedulers, risk managers, and key stakeholders alike will be guided on providing only realistic input values for the SRA.

In this analysis, the effects of activity calendars in the SRA outputs are investigated. Activities are assigned with different calendars while holding all other parameters constant. A simple schedule was developed using Primavera P6 for a straightforward understanding of the relationship between the inputs and the SRA results generated from Acumen.

The output shows that the duration as inputs in the risk register represents working days and NOT calendar days. Furthermore, Acumen takes into account the activity calendars in determining the probabilistic completion dates of the activities.

See also:

Schedule Risk Analysis With Acumen: Different Activity Types

Different Delay Analysis Techniques

Building Information Modelling: The Future of Project Management

Activity Calendars (Case 04).

Input

Risk assigned to a project with different activity calendars.
1 risk mapped to a single activity.
1,000 iterations set in Deltek Acumen Fuse.
All other parameters are set to be the same in each case/project shown in Figure 1 below.

Figure 1. Primavera Schedule with Different Activity Calendars.

Table 1. Risk Input for Different Activity Calendars.

Output

Figure 2. Risk Exposure Histogram Generated from Acumen (see tabulated values in Table 2).

Figure 3. Risk Drivers Generated from Acumen (see tabulated values in Table 2).

Analysis

Tabulation of the results of Figures 2 and 3 are shown in Table 2 along with calculations for analysis.

Table 2. Results and Calculations

Though C04A and C04B have the same parameters in the risk input, the difference in the calendar used affected the worst case scenario (P100) date with the former finishing later (23-Sep-20) than the later (14-Aug-20). C04A has a 5-day workweek calendar while C04B is working on a 7-day workweek schedule.

Due to a year of non-working period between 01-Jun-20 to 31-May-21, this affected the P100 of C04C to complete on 23-Sep-21. Compared to C04A, this is also a year late with both cases using the 5-day workweek calendar with the difference on the 1-year non-working period for C04C.

C04D and C04E use the same calendars with work period on 1 & 2-Aug-19, 1 & 2-Oct-19, 1 & 2-Dec-19 and from 1-Aug-20. During the non-working days, no hits were accounted in the risk exposure diagram.

Takeaways

The duration in the risk register represents workdays and NOT calendar days.
Acumen takes into account the workdays or the activity calendars when determining the probabilistic completion dates (P-dates) of an activity.