Evaluation of Factors Influencing Assistant Referee Decisions in Determining "Offside" in Football

Background and study aim. The human factor and referee errors are an inherent part of football. The number of mistakes can be significantly reduced, but it cannot be completely eliminated. At the same time, we must understand the nature of the error, what exactly influences the occurrence of the mistake, which part of the error is a subjective factor, and which part is an objective factor that is less susceptible to correction and does not depend on the referee's practice, experience, and training. This study is based on the procedure and factors that influence decision-making in the context of Law 11 (Offside). Decisions regarding the "offside" position are made by assistant referees and are among the most complex and discussed topics among experts and fans. The goal of the study is to determine the factors influencing the assistant referee's decisions when determining "offside" in football. Material and methods. The study involved 33 football assistant referees of different qualifications, including assistant referees from the Youth Football League of Ukraine, the Professional Football League of Ukraine, and the Ukrainian Premier League. The following research methods were used during the study: non-interventional observation, where regular observation was conducted from the side to study the decision-making process on the football field; video content analysis, where the technical aspects of referees' behavior were assessed; statistical methods to process the quantitative data obtained during experiments and observations; and the modeling method, which involved creating 3D computer models to analyze the impact of assistant referees' positions on the assessment of situations related to the interpretation of Law 11. Results. The conducted research allowed for the identification factors that influence the decision-making process regarding the determination of the "offside" position. Conclusions. Factors influencing the decision-making process regarding the determination of the "offside" position have been identified: AR's position relative to the offside line, focus shift to the player making the pass, level of concentration, movement of attacking and defending players, attacking players in offside position and possible movement of defenders, number of attacking and defending players, type of AR movement along the sideline, head, torso, and body movements, distance between attacking and defending players, fatigue, color of stands and advertising boards, style of the football field’s grass cutting.