Simulation Generate Node

The Simulation Generate node provides an easy way to generate simulated data, either without historical data using user specified statistical distributions, or automatically using the distributions obtained from running a Simulation Fitting node on existing historical data. Generating simulated data is useful when you want to evaluate the outcome of a predictive model in the presence of uncertainty in the model inputs.

Creating data without historical data

The Simulation Generate node is available from the Sources palette and can be added directly to the stream canvas.

  1. Click the Sources tab of the nodes palette.
  2. Drag and drop or double-click to add the Simulation Generate node to the stream canvas.
  3. Double-click to open its dialog box and specify fields, storage types, statistical distributions and distribution parameters.

Note: Simulation Generate nodes that are selected from the Sources palette will be completely blank, with no fields and no distribution information. This enables you to entirely create simulated data without historical data.

Generating simulated data using existing historical data

A Simulation Generate node can also be created by executing a Simulation Fitting terminal node:

  1. Right-click on the Simulation Fitting node and choose Run from the menu.
  2. The Simulation Generate node appears on the stream canvas with an update link to the Simulation Fitting node.
  3. When generated, the Simulation Generate node inherits all of the fields, storage types, and statistical distribution information from the Simulation Fitting node.

Defining an update link to a simulation fitting node

You can create a link between a Simulation Generate node and a Simulation Fitting node. This is useful if you want to update one or more fields with the information of the best fitting distribution, determined by fitting to historical data.

  1. Right click on the Simulation Generate node.
  2. From the menu, select Define Update Link. The cursor changes to the Link cursor.
  3. Click on another node. If this node is a Simulation Fitting node, a link is made. If this node is not a Simulation Fitting node, no link is made, and the cursor changes back to a normal cursor.

If the fields in the Simulation Fitting node are different to those in the Simulation Generate node, a message is displayed informing you that there is a difference.

When the Simulation Fitting node is used to update the linked Simulation Generate node, the result depends on whether the same fields are present in both nodes, and if the fields are unlocked in the Simulation Generate node. The results of updating a Simulation Fitting node are shown in the following table.

Table 1. Results of updating a Simulation Fitting node
  Field in Simulation Fitting node
Field in Simulation Generate node Present Missing
Present and unlocked. Field is overwritten. Field is deleted.
Missing. Field is added. No change.
Present and locked. The distribution of the field is not overwritten. The information in the Fit Details dialog box and the correlations are updated. The field is not overwritten. The correlations are set to zero.
Do not clear Min/Max when refitting check box is selected. The field is overwritten, apart from the values in the Min, Max column.
Do not recalculate correlations when refitting check box is selected. If the field is unlocked, it is overwritten. The correlations are not overwritten.

Removing an update link to a simulation fitting node

You can remove a link between a Simulation Generate node and a Simulation Fitting node by taking the following steps:

  1. Right click on the Simulation Generate node.
  2. From the menu, select Remove Update Link. The link is removed.