Title Pending 1691

Outcome bias is a pervasive phenomenon in decision-making, referring to the tendency to evaluate decisions made under identical circumstances as more favourable when it results in the desired outcome. This paper analyses this cognitive bias in the context of top-flight European football, examining whether a Bayesian updating model distorted by a multiplicative outcome bias is valid. Managers make significantly more changes to their strategy following a loss than a win, even having controlled for expected performance, in-game performance, and team and game-specific variation. The results of this paper are consistent with a positive-outcome bias, but not necessarily a multiplicative bias.