| Variables | Definitions | Notations | Sources |
| Gross Domestic Product | Real gross domestic product is an indicator of the level of economic activity. | GDP | Center for Research and Expertise on The World Economy (CEPII). |
| Distance | The distance (in km) between two countries | DIST | Center for Research and Expertise on the World Economy (CEPII). |
| Bilateral Real Exchange Rate | The uncertain real exchange rate of currency of i expressed in that of j | RER | International Financial Statistics (IFS) |
| Language | Is a dummy variable which takes the value 1 if the two countries share the same language and 0 otherwise. | Comlang | Center for Research and Expertise on the World Economy (CEPII). |
| Governance | Global Governance Indicator | GGI | Worldwide Governance Indicators (WGI) |
| The tariff variable | Tariffs applied to products from EU countries (j) to Tunisia (i). | Tariffs applied | Database TRAINS (Trade Analysis and Information System) |