Expressions

The document describes the functionality of expressions in LEAP, which are mathematical formulae used to define variable values in the Analysis View for both historical data and future scenarios. It details the various methods for editing expressions—including the Expression Builder, Time-Series Wizard, and Function Wizard—and explains the system of expression inheritance, where scenarios can inherit data from parent scenarios to reduce manual entry. The guide also covers color-coding for identifying expression sources, the ability to reference both data and results variables to create endogenous models, and the 'Expression Elaboration' feature for tracking dependencies between variables.

• Expressions in LEAP are mathematical formulae used to define variable values; they specify historical values in Current Accounts and define how variables change over time from the First Scenario Year to the End Year in scenarios.
• LEAP utilizes a hierarchical expression inheritance system to minimize data entry, allowing scenarios to inherit data from ancestor scenarios unless a different value is explicitly entered.
• The software uses a specific color-coding system in the Analysis View to indicate the origin of an expression: purple for explicit entry, black for inheritance from another scenario or region, green for inheritance from another region in multi-region sets, silver for default expressions, and red italics for errors.
• Users can create models with both exogenous and endogenous variables by referencing data variables (specified in Analysis View) and results variables (calculated internally by LEAP). Referencing results variables generally requires the PrevYearValue function to access values from a previous year, except when specifying calculated Indicator variables.
• The Expression Elaboration feature provides a dedicated tab in the Analysis View that lists the branches and variables a current expression depends on, as well as which branches, variables, and scenarios depend on the current branch.

APA

Stockholm Environment Institute (n.d.). Expressions. https://cdn.leap.sei.org/Help24/Concepts/Expressions.htm

Chicago

Stockholm Environment Institute. Expressions. n.d. https://cdn.leap.sei.org/Help24/Concepts/Expressions.htm.

Wikipedia

{{cite report |author=Stockholm Environment Institute |title=Expressions |url=https://cdn.leap.sei.org/Help24/Concepts/Expressions.htm |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{stockholmenvironmentinstitutendexpressions, author = {{Stockholm Environment Institute}}, title = {{Expressions}}, institution = {Stockholm Environment Institute}, url = {https://cdn.leap.sei.org/Help24/Concepts/Expressions.htm}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }