Description

Many of the inputs to a STEM model can be described as time series. A number of alternative constructions are provided, which allow you to provide a concise specification for the evolution of a time series, without necessarily having to specify an explicit value for each year of the model run. You can also define a time series with a numeric formula, using operators and functions to combine numbers and other time-series data – see 4.7 Viewing and editing time series – and some special inputs can be defined as, e.g., the Output of a Transformation.

Time-series inputs can be displayed as graphs directly in the Editor, providing an immediate preview of the way that STEM will interpret the parameters you have specified. Graphs can be displayed as tables, if you want to check the precise value in a particular year.

See also

In the STEM Editor, a time series appears as a button, which leads to a dialog where you can edit the parameters of a particular construction as a collection of inner fields. Each construction requires a different set of inputs, so the dialog for the inner fields has an additional menu which allows you to change from one construction to another.

The following types of time-series inputs are available:

- Constant
- Straight Line
- Exponential Growth
- Multiplier
- S-Curve
- Dual S-Curve
- Interpolated Series
- Transformation, Market Segment or Location
- Time-Series Formulae.

These are considered in turn in sections 10.3.33.1 Constant to 10.3.33.9 Time-series formulae. The annual interpretation of these types is broadly the same if you run a model with shorter time periods. The subsequent sections then explain how these types are evaluated for sub-annual periods – see 10.3.33.10 Specifying inputs for shorter time periods, 10.3.33.11 Using alignment to relate periods and 10.3.33.12 Using steps to constrain time-series inputs.

- 10.3.33.1 Constant
- 10.3.33.2 Straight Line
- 10.3.33.3 Exponential Growth
- 10.3.33.4 Floor and Multiplier
- 10.3.33.5 S Curve
- 10.3.33.6 Dual S Curve
- 10.3.33.7 Interpolated Series
- 10.3.33.8 Transformation, Market Segment or Location
- 10.3.33.9 Time series formulae
- 10.3.33.10 Specifying inputs for shorter time periods
- 10.3.33.11 Using alignment to relate periods
- 10.3.33.12 Using steps to constrain time series inputs

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