Does video assistant referee technology change the magnitude and direction of home advantages and referee bias? A proof-of-concept study

Table 1 Comparison of HA and referee bias in matches played with and without VAR

	Variables ^a	Descriptive statistics				Independent Samples t-test					TOST results for statistical equivalence H0: (d ≤ − 0.20 U d ≥ 0.20) vs. H1: (-0.20 < d < 0.20)
		Home Team		Away Team		Independent Samples t-test
		M	SD	M	SD	t	p	ES	BF₀₁ (H0/H1) ^b		Lower bound	Upper bound	Statistical equivalence
NO VAR (n: 918)	Points	1.65	1.33	1.11	1.28	8.92	< 0.001	0.42	0.00	-	t = 5.63 ^ns	t = 12.21 ^***
	Goals	1.58	1.30	1.21	1.17	6.48	< 0.001	0.30	0.00	-	t = 3.01 ^ns	t = 9.951 ^***
	Fouls	15.64	4.24	15.63	4.41	0.05	0.961	0.00	19.04	Strong	t = -0.94 ^ns	t = 1.04 ^ns
	Yellow cards	2.18	1.36	2.35	1.40	-2.63	0.009	-0.12	0.62	-	t = -5.74 ^***	t = 0.48 ^ns
	Red cards	0.12	0.34	0.15	0.42	-1.40	0.162	-0.07	7.24	Substantial	t = -12.56 ^***	t = 9.76 ^***	X
	Offsides	2.09	1.61	1.92	1.67	2.29	0.022	0.11	1.41	Anecdotal	t = -0.32 ^ns	t = 4.90 ^***
	Penalties	0.20	0.44	0.14	0.36	3.36	< 0.001	0.16	0.07	-	t = -7.27 ^***	t = 13.98 ^***	X
VAR (n: 920)	Points	1.63	1.31	1.11	1.25	8.70	< 0.001	0.41	0.00	-	t = 5.34 ^ns	t = 12.05 ^***
	Goals	1.58	1.28	1.19	1.12	7.04	< 0.001	0.33	0.00	-	t = 3.47 ^ns	t = 10.61 ^***
	Fouls	13.36	3.81	12.80	3.75	3.21	0.001	0.15	0.12	-	t = 2.07 ^ns	t = 4.34 ^***
	Yellow cards	2.11	1.37	2.25	1.39	-2.13	0.033	-0.10	2.02	Anecdotal	t = -5.24 ^***	t = 0.98 ^ns
	Red cards	0.12	0.36	0.15	0.039	-1.31	0.191	-0.06	8.16	Substantial	t = -12.78 ^***	t = 10.16 ^***	X
	Offsides	1.99	1.62	1.86	1.52	1.81	0.071	0.08	3.78	Substantial	t = -0.92 ^ns	t = 4.53 ^***
	Penalties	0.23	0.49	0.17	0.40	3.14	0.002	0.15	0.14	-	t = -6.50 ^***	t = 12.78 ^***	X

ISSN: 2052-1847