When you are building a STEM model, it is often useful to consider a range of possible values for certain key parameters in the model, as a way of quantifying the likely impact on results of uncertainties in your input assumptions. A ‘scenario’ is one particular set of key parameters, which can be run alongside and compared with other scenarios of the same model.
STEM provides a sophisticated mechanism for identifying key scenario parameters and editing time-series data for multiple scenarios, which allows a common model structure to be integrated with clearly labelled scenario data without resort to manual duplication of data in separate model files.
The following sections explain how this mechanism allows you to define multiple scenarios for a single input, and then how this process extends to varying several inputs together, or even varying separate groups of inputs independently.
For the sake of clarity, an extremely simple model, comprising just one service and one resource, is used to illustrate these principles.