Research
Variable dictionary, methodology, and citation policy
Documentation endpoint for the Maddison Project Database. Returns the two variables (GDP per capita and population) with their units and methodology notes, the 8 regional slugs and their canonical names, the release metadata (version, DOI, DataverseNL URL), the CC BY 4.0 citation policy including the special rule requiring per-country source citations for analyses covering fewer than 12 countries, and a short and full academic citation string. Published by Bolt and van Zanden at the University of Groningen under CC BY 4.0.
get/api/v1/research/maddison/definitions
Response
Variable dictionary, region list, methodology, and citation policy.
Example response
{
"data": {
"variables": [
{
"id": "gdppc",
"label": "GDP per capita",
"unit": "2011 international dollars (PPP)"
}
],
"regions": [
{
"slug": "western-europe",
"name": "Western Europe"
}
],
"citation_short": "Maddison Project Database (Bolt & van Zanden, University of Groningen, CC BY 4.0)",
"release": {
"version": "MPD2023 v1.0",
"doi": "10.34894/INZBF2",
"published": "2024-04-26T00:00:00Z",
"url": "https://dataverse.nl/dataset.xhtml?persistentId=doi:10.34894/INZBF2",
"file": "mpd2023_web.xlsx"
},
"known_historical_codes_absorbed": [
"SUN",
"YUG",
"CSK",
"SCG"
]
},
"meta": {
"endpoint": "/api/v1/fred/us/cpi",
"data_time": "2026-04-16T14:30:00Z",
"response_time": "2026-04-16T14:30:12Z",
"provider": "Sugra API v1.0.1",
"source": "sugra_crypto",
"attribution": "Short interest and Reg SHO daily short volume data is owned by and sourced from FINRA (Financial Industry Regulatory Authority).",
"fallback_chain": [
"sugra_crypto",
"sugra_finance"
]
}
}