MAMS (Maquette for MDG Simulations) is a tool for analysis of the effects of policies and external shocks on the World Bank’s twin goals (poverty eradication and promotion of shared prosperity) and other indicators. The analysis is done for individual countries and typically focused on medium- to long-run effects. To date, MAMS has been applied to more than 50 countries. It may help in addressing questions like: What are the impacts of an oil world price shock on the twin goals, GDP growth, and the sectoral structure of production and trade? Given projected GDP growth, tax policies, and government borrowing, what fiscal space exists for growth in government spending? How may alternative uses of such fiscal space influence progress on targets for the MDGs and the SDGs (Sustainable Development Goals) that will come in place in 2015?
Technically MAMS is an open-economy, multi-sector dynamic Computable General Equilibrium (CGE) model. MAMS and other CGE models offer a disaggregated and comprehensive view of the economy. They are particularly helpful in the analysis of policies and shocks with a broad impact on markets, the balance of payments, and the government budget. To exemplify, a CGE model may be indispensable if one tries to understand the impacts of significant import tariff cuts or of an upsurge in the stock of remittance-sending workers abroad. In both cases, the effects are broad, reaching labor markets, sectoral trade and production, and the balance of payments, with repercussions for wages, prices, the exchange rate, household incomes, poverty, and income distribution. Tariff cuts may also have repercussions for the government budget, with addditional effects on the economy as the government makes additional adjustments.
MAMS is a flexible tool that can be run in different versions that differ in data needs and analytical scope. For example, for analysis of macro issues, it is sufficient to use the core version with an aggregated database, which can easily be put together. Analysis emphasizing human development requires the MDG version with a more detailed database. Compared to other CGE models, the MAMS MDG version incorporates extensions that provide outcomes in terms of MDG indicators, and the educational make-up of the labor force, as well as the interaction of these outcomes with growth and other aspects of economic performance.
The use of MAMS has been greatly simplified thanks to the develpment of a user-friendly Excel-based interface – ISIM-MAMS is the name of MAMS with the interface – through which it is possible to select a country database and model version (core or MDG), define and run simulations, and access the results.
The economic performance indicators generated by MAMS include:
poverty, shared prosperity, and other MDG indicators (the latter only for the MDG version);
GDP (split into private and government consumption and investment; exports; imports);
the composition of the government budget, the balance of payments, and the savings-investment balance;
total factor productivity;
domestic and foreign debt stocks.
sectoral structure of production, employment, incomes, and trade;
the labor market: unemployment; educational composition of the labor force.
For the government, MAMS can simulate policies and shocks in terms of
spending: its level, efficiency, and allocation across different areas (which, for the MDG versions, typically includes education, health, and infrastructure);
financing: policies for taxation, domestic and foreign borrowing, and foreign aid.
For a one-page summary of the MAMS approach to MDG analysis, see p. 4 in the October 2012 issue of MDGs and Beyond. The Newsletter "KCP Perspectives" of January 2012 includes a story on the MAMS experience (pp. 3-4).
World Bank. 2015. Sudan Country Economic Memorandum: Realizing the Potential for Diversified Development. Washington, D.C., September. (For MAMS-related materials, drawing on input from Hans Lofgren, see pp. xviii-xx, 2-9, and 149-160.)
World Bank. 2015. Productivity in Bulgaria: Trends and Options. Document of the World Bank. June. MAMS-based analysis by Jouko Kinnunen (Statistics and Research Åland, Finland) with inputs from Hans Lofgren is presented in Chapter 8 (pp. 91-103). The task leader, Doerte Doemeland, made a presentation on the report at the World Bank in February 2016.
Sánchez, Marco V., and Rob Vos, editors. 2013. Financing Human Development in Africa, Asia and the Middle East. The United Nations Series on Development. Publisher: Bloomsbury Academic. How much would poor nations need to invest to eliminate poverty, get all children in school and provide adequate basic health care for all? Can they afford it? As part of their assessment of feasible strategies to enhance human development in pursuance of the Millennium Development Goals (MDGs), the contributors to this volume apply MAMS to nine countries in Africa, Asia, and the Middle East to (Egypt, Kyrgyzstan, Philippines, Senegal, South Africa, Tunisia, Uganda, Uzbekistan, and Yemen).
Lofgren, Hans. 2013. "Introduction to MAMS – A CGE Model for Developing Country Strategy Analysis." Presentation for the LCSPE and DECPG training workshop “CGE Modeling for Policy Analysis,” held at the World Bank, Washington, D.C., May 28.
Lofgren, Hans, Martin Cicowiez, and Carolina Diaz-Bonilla, 2013. “MAMS – A Computable General Equilibrium Model for Developing Country Strategy Analysis”. pp. 159–276 in Dixon, Peter B. and Dale W. Jorgenson, (Eds.), Handbook of Computable General Equilibrium Modeling. North Holland, Elsevier B.V.
Bourguignon, Francois, Carolina Diaz-Bonilla, and Hans Lofgren. 2008. "Aid, service delivery and the Millennium Development Goals in an economy-wide framework" (2.59 MB) World Bank Policy Research Paper no. 4683. Washington, D.C. Also pp. 283-315 in François Bourguignon, Luiz Pereira da Silva, and Maurizio Bussolo, eds., The impact of economic policies on poverty and income distribution - Macro-Micro Evaluation Techniques and Tools. New York: Palgrave.
On this page, we provide links to studies based on MAMS, carried out by the World Bank and/or its development partners, including UN-DESA, UNDP, governments, and other institutions carrying out research on development policy.
Robinson, Sherman and Hans Lofgren. 2008. Economy-Wide Models and Poverty Analysis. Presentation delivered by Sherman Robinson at the WIDER Conference “Frontiers of Poverty Analysis,” held in Helsinki, Finland, September 26-27.
Robinson, Sherman, Antonio Yunez-Naude, Raul Hinojosa-Ojeda, Jeffrey D. Lewis, and Shantayanan Devarajan. 1999. "From stylized to applied models: Building multisector CGE models for policy analysis." North American Journal of Economics and Finance, Vol. 10, pp. 5–38.
TIPS (Trade and Industrial Policy Strategies), Pretoria, South Africa. Downloadable materials used for the 2007 "Introductory Course on Computable General Equilibrium Modeling", offered by Dirk Ernst van Seventer and Rob Davies.
The World Bank website provides access to a wide range of materials, including data and information about research, publications, topics, and activities in different countries.
Links to external organizations
EcoMod Network. The Network, which is global, promotes model-based policy analysis. Among other things, website provides information about its activities, including courses and conferences.
General Algebraic Modeling System (GAMS). MAMS and many other CGE models are written in GAMS, a system for mathematical programming and simultaneous equation modeling. The website of the GAMS Development Corporation provides access to documentation, manuals and the software (a license is required to be able to solve anything but small models).
Global Trade Analysis Project (GTAP). GTAP is a global collaborative network that promotes model-based policy analysis and database development, both global and at the country level. Its website is an excellent source of data, documents and research outputs.
The Development Policy Analysis Division (DPAD) of the UN Department of Economic and Social Affairs (DESA) maintains a webpage for Capacity Development Publications, focused on applications macro-micro modeling, linking CGE models (including MAMS) to microsimulation models, including documents in Spanish.
Thomas Rutherford, of the University of Colorado in Denver, has developed numerous tools that facilitate GAMS-based modeling.