The Maddison Project, also known as the Maddison Historical Statistics Project, is a project to collate historical economic statistics, such as GDP, GDP per capita, and labor productivity. It was launched in March 2010 to continue the work of the late economic historian Angus Maddison. The project is under the Groningen Growth and Development Centre at the University of Groningen, which also hosts the Penn World Table, another economic statistics project.
Development economist Branko Milanović (writing for the World Bank), development economist Morten Jerven, and billionaire philanthropist Bill Gates have identified the Maddison Project, the Penn World Tables, and World Bank/IMF data (the World Development Indicators), as the three main sources of worldwide economic statistics such as GDP data, with the focus of the Maddison Project being on historical data. Economist Paul Krugman has suggested the Maddison Project as a data source for historical debt, growth, and labor output and productivity data. The relevance of these data for development decisions rather than for post facto analysis has been challenged as has the validity of many of the comments made by Morten Jevern in 'Poor Numbers' which sparked much of the current debate. 
- Penn World Table
- World Development Indicators
- The World Economy: Historical Statistics, a 2004 book by Angus Maddison that is an early precursor of the work done by the Maddison Project
- Angus Maddison statistics of the ten largest economies by GDP (PPP)
- "Maddison Project". Retrieved October 3, 2017.
- Milanović, Branko (July 19, 2013). "The end of a long era". World Bank. Retrieved October 3, 2017.
- "The Database. Penn World Table version 9.0". Groningen Growth and Development Centre. Retrieved October 3, 2017.
- Jerven, Morten. "Why Do GDP Growth Rates Differ?". Retrieved October 3, 2017.
- Jerven, Morten. "Poor Numbers! What Do We Know About Income and Growthin in Sub-Saharan Africa?" (PDF). Retrieved October 3, 2017.
- Gates, Bill (May 8, 2013). "Bill Gates: how GDP understates economic growth. GDP may be an inaccurate indicator in sub-Saharan Africa, which is a concern for those who want to use statistics to help the world's poorest people". The Guardian. Retrieved October 3, 2017.
- Krugman, Paul (April 26, 2013). "Debt and Growth Data". New York Times. Retrieved October 3, 2017.
- Ladimeji, Dapo (March 2018). "'Poor Numbers'by Morten Jevern - a critical review" (PDF).
- "Economic Growth § Data Sources". Our World in Data. 2017. Retrieved October 21, 2017.