Configuring and Running

During simulation, uncertainty is applied in the following order: floating (if applied), then duration ranges, then risk impacts.

With non-summary schedules, it is recommended to keep the number of iterations below 1,000 and use Latin Hypercube to achieve convergence quicker. A simulation with 1,500 activities and 1,000 iterations will take approximately 3 minutes to complete (this may be slower or faster depending on your computer specs). Non-work modeling and floating will increase the time required during simulation. 

1. Click the Simulations 

   

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2. Click the New button in the Simulation Properties pane.
3. Modify the parameters as needed.
4. Click Run.

The Timestamp column shows the date and time the simulation completed in the UTC "timezone". Depending on daylight savings, this is typically 4 hours ahead of US Eastern Standard Time (EST) or 2 hours behind Central European Time (CET). 

Deleting Simulations

1. Click the Simulations 

   

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2. Select the desired simulation in the table
3. Click the Delete button below the table.

As simulations are selected in the table, the Simulation Properties pane updates automatically.

Simulation Parameters

Parameter	Definition
Name	A text field for summarizing the simulation.
Method	The technique used for sampling. Whereas Monte Carlo uses repeated sampling, Latin Hypercube uses weighted sampling based on the number of iterations and the size of the range.
First Build	The actual schedule used as the baseline for every simulation, which could be the deterministic schedule, but could also be the mean or mode, as calculated from the duration ranges of all the activities.
No. Iterations	The amount of times, or passes through the schedule, that sampling will take place.
Seed	The value that tells the random number generator where to begin, allowing the same sequence of random numbers to be generated over time. At the beginning of each simulation, the random number generator is seeded by converting the timestamp to a UNIX timestamp, and then it's stored for future reference.
Calculate Risk Priority	With risk priority, the simulation is ran multiple times, each time removing the risk with the highest schedule or cost risk sensitivity, until no risks are left. For more info, see Risk Priority below.
Schedule Driven	An option for choosing how risk priority will be calculated. When selected, risks with the highest schedule risk sensitivity are removed. If no schedule uncertainty has been included on the risk, ranging tabs, or non-work views, it will be disabled.
Cost Driven	An option for choosing how risk priority will be calculated. When selected, risks with the highest schedule risk sensitivity are removed. If no cost uncertainty has been included on the risk or ranging views, it will be disabled.
Snap Project Start	An option for determining if the project start will be snapped to the start of the earliest object in the network. For projects that were imported from XER files, this will always occur.
Snap Project Completion	An option for determining if the project completion will be snapped to the finish of the latest object. When checked, the project completion snaps for the first build and then remains fixed for all subsequent iterations. For projects that were imported from XER files, this will always occur unless a planned completion date was entered.
Float Risk Envelope	When checked, the simulation is automatically re-ran multiple times for comparing the effect of float-use on the completion date.  For more info, see float below.
All Activities	When checked, a cumulative curve is generated where all activities with float during a given iteration consume the float according to the percentage entered below.
By Activity	When checked, a cumulative curve is generated where only the activities with float consumption specified on the Ranging tab consume the float specified.
Float Use (%)	Used in tandem with All Activities for specifying the percentage of float to be consumed out of available float at the time the activity starts during an iteration.
No. Iterations (%)	Used in tandem with All Activities for specifying the percentage of iterations to apply floating.

Risk Priority

With risk priority, a simulation is ran multiple times, each time removing the risk with the highest impact from the prior run, until no risks are left. Highest impact is determined from the risk sensitivity, or the correlation between the probability of the risk and the project completion date. The sensitivity can be based on schedule or cost, depending on what was included for simulation and what the user decides.

The result is the Risk Priority tornado chart organizing risks by the potential number of days or dollars that could be gained if they were to be mitigated, from highest to lowest. For example: imagine a schedule with three risks, Risk A, Risk B, and Risk C, and schedule-driven. The simulation will proceed as follows:

Each run of the simulation is organized under a parent group in the Simulation tab. Individual runs cannot be deleted.

Any risk with a strategy of "Accept" in the risk register will NOT be removed during simulation, regardless of its sensitivity.

Sensitivity is calculated using the Spearman Rank Method. For more info, see Results and Reporting.

Only risks with a checkmark in the "Include in Simulation" column will take place during simulation.

Float-use Risk Envelope

Traditional schedule simulation places all activities on early starts, ignoring the impact of delayed or late starts (i.e. the risk of float use) on project completion. However:

• In the real-world, contractors and owners use float conscientiously through the project 

• This can be to level resources, pace with other delays, or for other strategic reasons

• This presents a huge risk, since floated activities can then succumb to risks and duration overruns themselves

With the float-use risk envelope, the simulation is re-ran automatically multiple times for comparing the effect of float-use on the completion date. The result is the Float Risk Envelope distribution chart. Cumulative curves can be generated for the following scenarios:

Available Table Columns

For details on customizing columns, filtering, sorting, and organizing by WBS, see Interface Tour.