Table 4. Referee cumulative statistics from 2013 to 2021 in Serie A. The values shown correspond to the percentages of fouls, penalties, and cards whistled against the home teams.

p.g. = per game; SEM = standard error of the mean.

Seasons	% Fouls	% Penalties p.g.	% Yellow cards	% Red cards
2013-2014	50.0	26.1	48.2	45.8
2014-2015	48.6	56.1	47.4	44.1
2015-2016	49.0	35.6	46.8	40.6
2016-2017	50.6	39.0	47.0	37.1
2017-2018	47.1	44.1	47.2	40.7
2018-2019	48.1	35.4	46.5	43.3
2019-2020	50.8	49.1	48.3	45.1
2020-2021	49.7	53.6	50.1	40.6
Average 2013-2019	48.9	39.4	47.2	41.9
SEM	0.5	4.1	0.2	1.3
Average 2019-2021	50.3	51.4	49.2	42.9
SEM	0.5	2.3	0.9	2.3
Δ%	2.8	30.4	4.3	2.2
t	1.8	2.6	2.2	0.4