The Reliability of Technical and Tactical Tagging Analysis Conducted by a Semi-Automatic VTS In Soccer

Abstract

The Video Tracking multiple cameras system (VTS) is a technology that records two-dimensional position data (x and y) at high sampling rates (over 25 Hz). The VTS is of great interest because it can record external load variables as well as collect technical and tactical parameters. Performance analysis is mainly focused on physical demands, yet less attention has been afforded to technical and tactical factors. Digital.Stadium® VTS is a performance analysis device widely used at national and international levels (i.e. Italian Serie A, Euro 2016) and the reliability evaluation of its technical tagging analysis (e.g. shots, passes, assists, set pieces) could be paramount for its application at elite level competitions, as well as in research studies. Two professional soccer teams, with 30 male players (age 23 ± 5 years, body mass 78.3 ± 6.9 kg, body height 1.81 ± 0.06 m), were monitored in the 2016 season during a friendly match and data analysis was performed immediately after the game ended. This process was then replicated a week later (4 operators conducted the data analysis in each week). This study reports a near perfect relationship between Match and its Replication. R2 coefficients (relationships between Match and Replication) were highly significant for each of the technical variables considered (p < 0.001). In particular, a high score of interclass correlation and a small coefficient of variation were reported. This study reports meaningless differences between Match and its Replication (intra-day reliability). We concluded that the semi-automatic process behind the Digital.Stadium® VTS was more than capable of recording technical tagging data accurately.

The Validity and Reliability of Live Football Match Statistics From Champdas Master Match Analysis System

“…From professional football coaches’ evaluation, match variables included in the system had high levels of content validity. Operators separately coded more than 4,000 events in each data collection, which was higher than the values from previous studies applying other systems such as Prozone, OPTA and Digital.Stadium (Bradley et al, 2007; Liu et al, 2013; Beato et al, 2018). Moreover, results reported in this study showed that Champdas Master System had high levels of absolute and relative reliability.…”

“…The questionnaire was based on performance variables used by Champdas Master System and they were divided into three domains: (i) Attacking-related performance; (ii) Passing-related performance, and (iii) Defending-and-Goalkeeper-related performance. The criterion of selecting these variables were mainly based on two categories of existing literature, namely, studies that examined the validity of other match analysis systems and analyzed variables (Valter et al, 2006; Bradley et al, 2007; Liu et al, 2013; Castellano et al, 2014; Beato et al, 2018); and studies that focused on tactical patterns and passing behaviors of football players (Rein et al, 2017; Goes et al, 2019; Pollard, 2019). Within all variables, the inclusion of two variables should be highlighted.…”

“…To test the system reliability, four well-trained operators (experience = 1.5, 1.5, 2, and 2 years) from Champion Technology Co., Ltd., collected twice (with an interval of 2 weeks) the match data of the 19th round of Spanish La Liga Santander between Real Madrid and Villarreal contested in January 13, 2018 (Live broadcast from a conventional TV coverage). The number of match used and the coding procedure followed the routine of previous studies that validated similar systems (Bradley et al, 2007; Choi et al, 2007; Liu et al, 2013; Beato et al, 2018).…”

“…Therefore, as a prerequisite for any performance analysis research that uses novel system or instrument, the repeatability and accuracy of this new tool, and the validity of performance indicators used should be validated, before collecting and analyzing players and teams’ performances (O’Donoghue, 2014; Chacón-Moscoso et al, 2018). Despite that currently there are some automatic player tracking system available for performance analysis, most of observational studies or practices in sport field are still done with computerized notational systems where performance analysts are required to manually code sport performance indicators with predetermined short-cut keys (Bradley et al, 2007; Hizan et al, 2010; Liu et al, 2013; Beato et al, 2018). From a theoretical and applied perspective, a performance indicator should help to explain the match outcome; and thus advance understanding, providing for meaningful insights of game behavior (O’Donoghue, 2009).…”

“…It refers to the reproducibility of values of a test, assay or other measurement in repeated trials on the same individuals (intra-observer reliability) (O’Donoghue, 2009), and repeatability over different observers (inter-observer reliability) (Hopkins, 2000). Sports notational system may be limited in reliability due to manual errors, observer’s inexperience, number of observers (Beato et al, 2018) so that its results will mislead coaches or performance analysts to make poor decisions about training and match preparation.…”