Variables collected by reviewers for analysis for each head collision event (HCE) identified
| Variable | Description |
| No. players involved | The number of players involved in the HCE, including the injured player (numerical) |
| Medical assessment | Whether the injured player received assessment from team medical personnel (binary) |
| Assessment location | The location where injured players were assessed by medical personnel, includes: no assessment, on field, on sidelines, elsewhere in the stadium/hospital |
| Time assessed | Time that injured player was assessed by medical personnel until return to play in seconds (s) |
| Return to play | Time until injured player returned to play, includes: immediately following assessment on pitch, immediately following assessment on sidelines, in the same half, removed from game, removed from game via APCS |
| Score | Score of the game in reference to the injured player’s team, includes; tied, winning, losing |
| Foul | Whether the referee determined there was a foul for the HCE (binary) |
| No. signs of concussion | The number of signs of concussion demonstrated by the injured player, includes: slow to get up, clutching of the head, disorientation/daze, loss of consciousness, obvious disequilibrium |
APCS, additional permanent concussion substitute.