Using composite performance variables to explain football players' market values

PurposeThe Norwegian football app FotMob (https://www.fotmob.com/) has recently introduced a new and novel composite performance variable or index. The present study examines how this composite performance index is associated with football players' market values as defined by the Norwegian website FotMob and by the German website Transfermarkt.MethodsUsing data on the players in the Norwegian top-tier league for the 2022 season, FotMob's performance index' effect on FotMob's and Transfermarkt's market values is estimated by team-fixed effects regression models also controlling for several key independent variables typically used in prior and best-case regression models.ResultsFotMob's composite performance index has a statistically and practically significant effect on football players' market values. Yet the magnitude of this index' effect is contingent on other key independent variables' effects (i.e. interaction effects). Not adjusting for the index also overestimate other key independent variables' effects on football players' market values.Contributions and implicationsShowing how a new and novel composite performance variable or index is associated with football players' market values, this study contributes to the literature on monetary valuation in football. The study's results generally suggest that composite performance indexes deserve to play a larger role in future football valuation research than they have done in the past.