| Independent variables | Meaning | Expectation |
| GDPj | GDP of the import country or region (j), indicating the economic scale of the importer | + |
| GDPi | GDP of Beijing, indicating the economic scale of the exporter | + |
| PGDPj | Per capita GDP of the import country or region (j), indicating the economic scale of the importer | + |
| PGDPi | Per capita GDP of Beijing, indicating the economic scale of the exporter | + |
| Eduj | Indicating the resident’s education in the import country or region (j) | + |
| Eudi | Indicating the resident’s education in Beijing | + |
| Culij | Indicating the cultural distance between the import country or region (j) and Beijing | ? |
| Lanij | Indicating the language differences between the import country or region (j) and Beijing | ? |
| Dij | Indicating the geographical distance between the import country or region (j) and Beijing | ? |