Uncertainty Analysis Run Control

The control panel at the bottom of the Uncertainty Input form sets parameters for the number of Replications and the Random Number Seed. The number of replications determines how many times the simulation is run for the uncertainty analysis. The greater the number of runs, the smoother the graphs will be. Number of replications can range between 2 and 100,000, although between 3,000 and 10,000 replications is suitable for most studies. The Random Number Stream provides control over the random numbers that are selected for the Monte Carlo sampling. The same set of random numbers will always be selected for a particular random number stream (the impact of this will vary depending on which inputs and which distributions are selected). Checking the Auto option will use a random selection for the random number stream - the randomly selected stream number will be shown in the results, allowing replication of those results by selecting that random number stream later.

Uncertainty analysis control panel

Uncertainty analysis control panel

The options for running an uncertainty analysis will differ depending on whether any correlation relationships are defined or not. If no correlations are defined then it is possible to pause the analysis, review the results and change the number of replications as required. Checking the Pause check box will pause the uncertainty analysis after the specified number of replications rather than stopping it, and it is then possible to extend the number of replications after reviewing the results. If correlations are defined then samples for all replications are generated before the first replication is run so that samples with the appropriate degree of correlation can be produced. It is not possible to change the number of replications during the run, therefore the Pause box is not enabled, although the analysis can be paused manually and the results reviewed, or the analysis can be stopped early.

The green Play button executes the runs. The simulation duration (i.e. the number of years represented) will be taken from the OSCAM setting that can be changed through the Simulation control dialog box. The Progress box will show what percentage of the replications has been completed, and the Status box will display the replication number that is being run. During the run the Play button which change to a Pause button and the Stop button will be enabled. All other control on the form are disabled so it is not possible to change settings while the uncertainty analysis is being run.

Uncertainty analysis control panel during a run

Uncertain anlysis control panel during a run

The Pause button will temporarily pause the simulation and display the results. You can return to the Uncertainty Input form by clicking the "Uncertainty Data Form" button. If no correlations are defined then you will be able to change the target number of Replications and change the checked status of the Pause check box. It is not possible to change uncertainty input definitions during a pause. You can click the Resume button to resume the uncertainty analysis run. It is possible to exit the Uncertainty Input form during a pause, but any changes to input values, or loading another data record will stop the uncertainty analysis. 

Uncertainty analysis control panel during a pause

Uncertainty control panel during a pause

The Stop button can be used to halt the set of runs. The run that is being executed when the button is clicked will finish executing but no further runs will take place. The output from the completed runs will be displayed.