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"
    ]
  }
}

Changes

Changed in 1 of the 21 revisions of this API.12

Aug 8, 20264c4530760ba112See the full diff
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  added the optional property code to the response with the 503 status
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  added the optional property hint to the response with the 401 status
  response-optional-property-added
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  added the optional property hint to the response with the 429 status
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  added the optional property hint to the response with the 503 status
  response-optional-property-added
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  added the optional property plan to the response with the 401 status
  response-optional-property-added
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  added the optional property plan to the response with the 429 status
  response-optional-property-added
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  added the optional property plan to the response with the 503 status
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  added the optional property reason to the response with the 401 status
  response-optional-property-added
- ○
  added the optional property reason to the response with the 429 status
  response-optional-property-added
- ○
  added the optional property reason to the response with the 503 status
  response-optional-property-added

Full history