Tornado chart
A tornado chart ranks the importance of the simulation inputs (parameters) on a specified output (at a specified timepoint). The rank coefficient for each input is represented by a horizontal bar with a value between -1 and 1, ordered from highest to lowest contribution to the output variability.
The tornado chart is a tool in sensitivity analysis and can only be created after a probabilistic simulation or a sensitivity analysis has been performed.
Tornado charts can help you:
- Find which parameters affect a specific simulation output the most (and the least).
- Illustrate correlations between parameters as set up in the parameter correlation settings.
Creating a tornado chart
From the results window (Recommended)
- Right-click an output that you wish to plot and select Tornado Chart from the popup-menu.
From the charts window
- Right-click the charts window and select Create | Tornado Chart from the popup-menu.
Editing a tornado chart
Some properties can be changed directly by using the controls below the chart. For a tornado chart there are controls for:
- Legend - Toggle legend on/off
- Correlation - Select ranking method (more information can be found below).
- Time-point - Select time point for the output.
To change other properties either right-click the chart in the charts window and select Edit, or double-click the chart, or click the 
button in the title bar.
The chart editor has two tabs:
Properties
This screen let you edit properties such as name and axes, that are common to most charts. Please see editing chart properties for more information.
Data
-
Output - Select the target output.
-
Inputs - Select the inputs you are interested in. By default all parameters that are included in the probabilistic/sensitivity analysis are selected.
-
Timepoint – For time dependent outputs, specify the time point you wish to plot.
-
Max number of bins – Limits the number of inputs that are shown in the chart. Default=10.
-
Type – Select which correlation ranking method you wish to use.
- Spearman’s rank correlation coefficient
- Pearson product-moment correlation coefficient
- Standardized regression coefficient
- Standardized rank regression coefficient
- Partial correlation coefficient
- Partial rank correlation coefficient