Table 1.
Co-occurrence analysis summary of e-cigarette ingredient data from the European Common Entry Gate system (EU-CEG) as available on 31 December 2022
| Product type | E-liquid | Disposable | Rechargeable | Refillable |
|---|---|---|---|---|
| Co-occurrence statistics | ||||
| Number of products | 33179 | 10970 | 248 | 51 |
| Number of significant ingredient pairs (network edges) | 214 | 13 | 43 | 0 |
| Number of unique ingredients (network nodes) | 62 | 19 | 41 | 0 |
| Network parameters | ||||
| Average number of connections per node | 7.5 | 1.8 | 2.5 | NA |
| Average distance between two nodes (characteristic path length) | 2.6 | 2.4 | 3.6 | NA |
| Largest distance between two nodes (network diameter) | 7 | 5 | 8 | NA |