Spencer, Bartholomew (2019) Spatiotemporal Analysis of Australian Rules Football. PhD thesis, Victoria University.

Abstract

Player tracking data has previously been used to quantify movement profiles in the Australian Football League (AFL), however little research exists into its use to measure the spatial interactions of players. This thesis presents new methodologies for measuring the spatial interactions and occupancy of players in team sports. Global positioning systems (GPS) and local positioning systems (LPS) spatiotemporal datasets were sourced from training sessions, Under-18s matches and elite-level AFL matches. Datasets were consolidated with play-by-play transactions to infer ball position. An initial pilot study investigated the relative importance of traditional performance indicators to inform the focus of later studies. Subsequent chapters investigated the relative phase of inter- and intra-team player couples and multiple approaches to the measurement of the spatial control of individuals. Gaussian mixture models (GMM) were used to estimate the density of player groups in order to analyse changes in congestion throughout a match. Player motion models fit on player displacements were combined with a measure of field equity to value the passing decisions of players. A new approach to player motion models was developed by fitting the weighted distributions of player commitment to contest events. The resultant models more realistically explain player behaviour in proximity to the ball. The models were used to measure the spatial control of teams, from which the spatial characteristics of passes in the AFL were extracted. Passes were clustered into three distinct styles. In the final chapter of this thesis, the models developed in the preceding sections are used to develop a new decision-making model. The expected outcomes of a player’s passing options are modelled through consideration of field equity, spatial control, kicking variance and possession outcomes. Using this model, passing decisions from the 2017 and 2018 AFL seasons were analysed. In contrast to previous studies, the value of a player’s decision is measured relative to their options, rather than to an increase in possession expectation. This thesis aims to derive insights into player movement behaviour in Australian football. Furthermore, the novel spatial metrics developed in this thesis have applications in player recruitment, coaching, and performance analysis.

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