## 3 Results  
The differences between match-related performance variables in the seasons with and without VAR are shown in Table 2. There was a significant decrease in the number of fouls (from 31.82 to 26.21, t = 23.865, \(p\) < 0.001, d = 0.93), yellow cards (from 4.59 to 4.32, t = 3.319, \(p\) < 0.001, d = 0.13), and offsides (from 4.04 to 3.71, t = 3.773, \(p\) < 0.001, d = 0.15) after VAR implementation. In contrast, there was a significant increase in the number of penalties (from 0.32 to 0.42, t = -3.812, \(p\) < 0.001, d = 0.11). According to [PERSON]'s d effect size classification, the reduction in fouls reflects a large effect, while the changes in yellow \begin{table}
\begin{tabular}{l l} \hline Goal & Number of goals scored. \\ Foul & Number of fouls committed. \\ Yellow Card & Number of yellow cards awarded to players by the referee for an infringement. \\ Red Card & Number of red cards awarded to players by the referee for an infringement. \\ Offside & Number of offside decisions by the referee. \\ Penalty & Number of penalties awarded. \\ \hline \end{tabular}
\end{table} 
Table 1: Match-related performance indicators. cards, offsides, and penalties correspond to small effects. The density graph of match performance indicators before and after VAR implementation is provided in Figure 1.  
According to the generalized linear model, there was a significant decrease in the number of fuels committed (B = \(-\)0.19, \(p\) < 0.001), offsides (B = \(-\)0.09, \(p\) < 0.001), and the incidence of yellow cards (B = \(-\)0.06, \(p\) < 0.001). Conversely, there was a significant increase in the number of penalty decisions (B = 0.25, \(p\) < 0.001). No statistically significant changes were observed in the number of goals scored (B = \(-\)0.02, \(p\) = 0.483) and red cards issued (B = 0.01, \(p\) = 0.943) (Table 3). According to the comparison of the four seasons in which VAR was implemented, the numbers of fuels (F = 23.386; \(p\) < 0.001) and offsides (F = 3.89; \(p\) = 0.019) were statistically significant. For fuels, VAR4 was the season with the fewest fuels, and these differences were significant compared to all previous seasons. In addition, there was also a significant difference between VAR-1 and VAR-3. For offside, VAR-3 was statistically different compared to VAR-4. After using VAR, we found no statistical differences between the \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Variables**} & \multicolumn{2}{c}{**No VAR (n:1224)**} & \multicolumn{2}{c}{**VAR (n:1412)**} & \multicolumn{4}{c}{**[PERSON]’s d 95\% CI**} \\ \cline{2-9}  & **Mean \(\pm\) SD** & **Mean \(\pm\) SD** & **t** & \(\mathbf{p}\) & **d** & **Lower** & **Upper** \\ \hline Goals & 2.81 \(\pm\) 1.69 & 2.76 \(\pm\) 1.68 & 0.693 & 0.489 & 0.03 & \(-\)0.05 & 0.10 \\ Fouls & 31.82 \(\pm\) 6.52 & 26.21 \(\pm\) 5.34 & 23.865 & \textless{}0.001 & 0.93 & 0.85 & 1.02 \\ Yellow & 4.59 \(\pm\) 2.10 & 4.32 \(\pm\) 2.12 & 3.319 & \textless{}0.001 & 0.13 & 0.05 & 0.21 \\ Red Cards & 0.28 \(\pm\) 0.57 & 0.28 \(\pm\) 0.56 & \(-\)0.067 & 0.946 & \(-\)0.00 & \(-\)0.08 & 0.07 \\ Offsides & 4.04 \(\pm\) 2.32 & 3.71 \(\pm\) 2.19 & 3.773 & \textless{}0.001 & 0.15 & 0.07 & 0.22 \\ Penalties & 0.32 \(\pm\) 0.57 & 0.42 \(\pm\) 0.66 & \(-\)3.812 & \textless{}0.001 & 0.15 & \(-\)0.23 & \(-\)0.07 \\ \hline \hline \end{tabular} Note. SD: standard deviation; 95% CI: 95% confidence interval.  
\end{table} 
Table 2: Differences between match performance variables with and without VAR. Figure 1: Density graph of match performance indicators before and after VAR implementation. seasons for the other variables (Table 4). For the density plot comparing seasonal match performance indicators before and after VAR implementation, please refer to Figure 2.