Game-Related Statistics in the Spanish Water Polo League: differences between Seasons

Abstract

The aim of this study was to identify the differences between seasons in meńs water polo regular competition by analysing the changes of game-related statistics. The sample comprised 88 games from the Spanish Professional Water Polo League (2011-2014). The game-related statistics were clustered into five groups: attacks in relation to the different playing situations, shots in relation to the different playing situations, attacks outcome, origin of shots and technical execution of shots. Univariate (ANOVA, Kruskal-Wallis and Generalized Linear Model tests) and multivariate (Discriminant) analyses were used to compare seasons, and statistical significance and effect sizes of the differences between seasons were calculated for the game-related statistics. The data were compositional data, therefore the variables were modified with additive log-ratio transformation. During the 2011-2012 season, the teams had significantly higher averages in even attacks (p<.01) and shots from zone 3 (p<.05). In the 2013-2014 season, teams had significantly higher averages in counterattack (p<.001), counterattack shots (p<.01), shots from zone 6 (p<.05) and 4 (p<.05). The variables that best distinguished between seasons were counterattack shots, counterattack, shots from zone 6 and 3, and even attacks. The group that best discriminated among seasons was «Origin of shots» (46.5% original sample and 42.3% cross-validation). The increase in counterattacks and in zone 6 shots seems to indicate a trend towards faster games and greater relevance of the centre forward. These findings can contribute to a better understanding of the evolution of water polo performance indicators, helping the coaches to prepare the players accordingly.