The sources of data
The source for international arms export data is the Stockholm International Peace Research Institute (SIPRI). International export values are measured in trend-indicator value (TIV).
As stated on SIPRI website:
“TIV is based on the known unit production costs of a core set of weapons and is intended to represent the transfer of military resources rather than the financial value of the transfer. […] TIV is intended to provide a common unit to allow the measurement of trends in the flow of arms to particular countries and regions over time. Therefore, the main priority is to ensure that the TIV system remains consistent over time, and that any changes introduced are backdated.”
A more extensive explanation of TIV can be found here.
The data on the arms export of the European Union’s member states, instead, are expressed in Euros. The data is originally published by the EU institutions and it was systematized and made more accessible by the NGO Campaign Against Arms Trade (CAAT) in their GitHub repository.
Member states share the data on their arms export by communicating the total amount of export licenses granted, and the actual export that took place, but not every member state shares information on the latter. Some EU countries — namely Belgium, Cyprus, Germany, Malta, and the United Kingdom — do not share the figures of actual exported goods but just the data on licences.
As CAAT does, I use a combination of export values (for the countries that share the export data) and license values (for the ones that do not) in order to show the arms export data of EU countries. On CAAT website you can find a thorough explanations of the data.
Matching export values with democratic index
I matched the data on European arms export with the democracy index measured by the Economist Intelligence Unit. The process is relatively simple: