Investigating the relationship between injury and match outcome in Australian Football League matches

The aim of this study is to investigate the relationship between injury and match outcome in Australian Football League (AFL) matches. Seven years of match betting odds, match injuries and final margins were analysed in two ways; from the perspective of the home (versus away) and favoured (versus unfavoured) team. Probabilities derived from betting odds at the start of the match were corrected for over-round and used to indicate the predicted match outcome. Final margin was used to represent actual match outcome. Linear regressions and t-tests were performed to examine the nature and strength of the relationships; the influence of predicted match outcome on match injuries, and of match injuries on actual match outcome. Predicted match outcome for the home and favoured team was uncorrelated with match injuries, thus suggesting against the theory that injuries are caused by unbalanced competition. In contrast, match injuries for the home (r = -0.19, p < 0.001) and favoured (r = -0.20, p < 0.001) team were negatively correlated with the actual match outcome. Compared to matches where both teams sustained the same number of injuries (home team = 9 point margin, favoured team = 27 point margin), home and favoured teams’ average final margin decreased (p < 0.01) when they sustained one or more injuries than the away (home team = -2 point margin) and unfavoured (favoured team = 16 point margin) team respectively. A home ground advantage is equivalent to approximately one match injury in the AFL. In conclusion, match injuries can influence the outcome of a match in the AFL, thus clubs that can find ways to reduce their match injuries have the potential to increase their likelihood of a successful match outcome.