Nexus SAMS for CGE modeling
In the context of economic and environmental analysis, Social Accounting Matrices (SAMs) are comprehensive, economy-wide databases that capture the transactions and transfers between different economic agents. They are used as a basis for CGE models, which are widely employed to analyze the economic impacts of various policies and changes.
The term “Nexus” in this context typically refers to the interlinkages between different sectors or aspects, such as the water-energy-food nexus, highlighting the interconnected nature of these resources. In CGE modeling, incorporating Nexus SAMS means integrating these interlinkages into the economic analysis, allowing for a more holistic understanding of how changes in one sector can impact others. This approach is particularly relevant in analyzing environmental policies, sustainability initiatives, and resource management strategies.
By integrating Nexus SAMS into CGE models, analysts can better assess the trade-offs and synergies among different policy objectives, such as economic growth, environmental sustainability, and resource use efficiency. This approach is increasingly important in the context of sustainable development and climate change mitigation strategies.
Nexus SAMs allow for more robust cross-country comparisons of national economic structure, especially agriculture-food systems. The guiding principles are that all data should be traceable to original sources and/or assumptions, and that all SAMs should be freely available online. Greater transparency and accessibility should facilitate more data validation and participation of the modeling community. Statistics are continuously being revised and errors are often only identified when data is used for analysis, and so we welcome your suggestions on how the SAMs can be improved to reflect new and/or better information.
The open access versions of Nexus SAMs separate domestic production into 42 activities. Factors are disaggregated into labor, agricultural land, and capital. Labor is further disaggregated across three education categories. The Nexus SAM defines household groups, namely rural and urban households disaggregated by per capita expenditure quintiles. The remaining accounts include enterprises, government, taxes, savings-and-investment, and the rest of the world.
Nexus SAMs are constructed using a Nexus SAM Building Toolkit developed by IFPRI. During the first stage, a Macro SAM is constructed from and fully consistent with official National Accounts, Government Finance Statistics, and Balance of Payments data. During the second stage, income and expenditure shares derived from household surveys and other sources are used to disaggregate the Macro SAM across multiple activities, commodities, factors, and households. Account imbalances are corrected through cross-entropy estimation.
Table: key Nexus SAMS
| Country | Data | Documentation |
|---|---|---|
| Kenya | 2021 | 2021 |
| Rwanda | 2021 | |
| Zambia | 2021 | 2021 |
| Ghana | 2013 2019 | 2019 |
| Malawi | 2014 2019 | 2019 |
For more information, possible other countries and previous years for mentioned countries please visit the Nexus project web page.