Second-leg home advantage in the Copa Libertadores da América (2005-2015)

A naive analysis was applied considering how many times a team that played the second leg at home qualified for the next round. To verify differences between home, away and draw results, the Chi-square ( χ² ) and the Full Bayesian Significance Test were applied. For the binomial variables ("Home" or "Away"), the probability of second-leg knockout occurrence was calculated.

Results

The probability of second-leg HA varied from 27.27% to 63.64% suggesting fluctuations of second-leg HA during competitive phases (round of 16, quarterfinals, semi-finals and final matches) and decision forms (full time, goals away rule or penalty-shoots).

Conclusion

The results counteract the common belief that there is a large advantage to playing the second match of a two-leg tie at home during all competition phases. Penalty-shots seemed to affect positively the second-leg HA. Despite the causes of second leg HA in CLA need to be better investigated, soccer coaches could to use these results to think better strategies to win your knockout matches.

Keywords:
soccer; knockout matches; South American football

		Chi-square	P- value	E -value

Aggregate Score	Eight-final	7.28	0.03	0.02
	Quarter-final	1.41	0.50	0.46
	Semi-final	2.82	0.24	0.23
	Final	4.55	0.10	0.08
	Total	10.36	0.01	0.00

Win form		Chi-square	P- value	E -value	P (p1>1/2)
Goals away rule
	Eight-final	0.14	0.70	0.68	0.36
	Quarter-final	1.80	0.18	0.13	0.89
	Semi-final	1.00	0.32	0.24	0.19
	Final	--	--	---
	Total	0.00	1.00	1.00	0.50

Penalty shoots	Eight-final	0.00	1.00	1.00	0.50
	Quarter-final	6.00	0.01	0.01	1.00
	Semi-final	1.00	0.32	0.25	0.75
	Final	0.00	1.00	1.00	0.50
	Total	2.56	0.11	0.09	0.94

	Chi-square	P- value	E- value	P (p1>1/2)	Predictive
Eight-final	0.05	0.83	0.83	0.58	0.51
Quarter-final	1.45	0.23	0.22	0.88	0.59
Semi-final	1.64	0.21	0.18	0.11	0.37
Final	2.23	0.13	0.11	0.93	0.70
Total	0.50	0.48	0.48	0.76	0.53

Full-time	0.03	0.86	0.86	0.57	-
Goals away	0.00	1.00	1.00	0.50	-
Penalties	2.58	0.11	0.09	0.94	-
Total	0.50	0.48	0.47	0.76	-

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E-mail: motriz.rc@unesp.br

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[1] Corresponding author: Cesar C. C. Abad. SENAC, Department of Physical Education, Centro Universitário SENAC, Avenida Engenheiro Eusébio Stevaux, 823, Santo Amaro, CEP: 04696-000, São Paulo/SP, Brazil. Email: c.cavinato@uol.com.br