Research on Home Team Advantage in the NRL

[tom620]

Just wanted to forward on some more research that recently came out.

Between 2001 and 2012, 114 games were played at a shared Sydney stadium with the co-sharer. In these cases, the main difference for the competitors has been assumed to be control of marketing the game, control of where members or the team’s fans sit, whether the team uses the home or away change room with some auxiliary changes to the control of schedules or use of the field for training purposes.

And yet, it is found that there is a notable difference in the probability of a home team win depending upon the stadium and opponent type.

When a match is played at a shared Sydney stadium against a sharer the probability of a home team win for the period between 2001 and 2012 is found to be 50.83% in comparison to 44.10% for a match at a shared Sydney stadium against a non-sharer.

An interesting result is that an unshared stadium and a match at a traditional Sydney stadium against a Sydney based rival were the most favourable home grounds during the 2001-2012 period.

These cases would be consistent with a match similar to:
- the Brisbane Broncos playing at Suncorp Stadium against an opponent that was only better on the table by one competition point and one field goal (unshared stadium), and
- the West Tigers versus the Manly Sea Eagles at Leichhardt Oval, if Manly were only better on the table by one competition point and one field goal (traditional Sydney stadium against a Sydney based rival).

All probabilities in this article should be interpreted with an advantage of a draw and a field goal in favour of the away team.

http://www.feem.it/getpage.aspx?id=6384

Based on the 2001-2012 average probabilities the most favourable stadiums to play at are ordered as:
1\. Unshared Stadium
2\. Traditional Sydney Stadium against a Sydney based rival
3\. Traditional Sydney Stadium against a non-Sydney rival
4\. Shared Sydney Stadium against a Sharer
5\. Marquee Stadium
6\. Shared Sydney against a non-Sharer

 

[tom620]

Here is a summary of the probability of a home team win for different stadiums.

Leichhardt and Campbelltown would be classified as Traditional Sydney Stadiums, with Homebush and the SFS being Shared Sydney Stadiums.

Note that Home Team Win Percentages are the actual percent of home team wins at the grounds and the probabilities have been adjusted to represent cases where the teams are almost equally matched in terms of competition points and for-against. (The probabilities are actually computed with 1 comp point and 1 field goal in favour of the away side)


 

[guyofthetiger]

Seems to support the case for not moving to ANZ full time…

 

[happy_tiger]

But how do our percentages aim up with this ??

You include Manly at Brookvale and they would probably have won at least 75 % of their home games

 

[tom620]

But how do our percentages aim up with this ??

You include Manly at Brookvale and they would probably have won at least 75 % of their home games

The probabilities are adjusted for opponent strength - so the fact that Manly have won 75% of home games also depends upon the quality of their team and the opponent they play at Brookvale.

Teams like the Tigers and the Bulldogs are easier to compare as they tend to play across a range of stadium types and you can look at things in the same successful/unsuccessful year. Based on win percentages, the Tigers do tend to fare better at Traditional Sydney grounds than there overall success dictates. Manly have a horrible record at Gosford and this is captured in the Marque numbers.
\
\
Based on win percentages here is something that I comment on with respect to the Tigers:

_Note that matches at a traditional Sydney home ground have been associated with improved success due to beneficial crowd support. In March 2014 a Sydney newspaper reported that once you exclude the Melbourne Storm in the period between 2007 and 2014, “the top three most successful home ground advantages all belong to suburban grounds - Manly at Brookvale (73%), Wests Tigers at Leichhardt (64%) and St George Illawarra at Jubilee (63%).” (Walshaw, 2014) On the matter of home ground advantage at Brookvale Oval the same report quotes a Manly player who states that “the crowd, the atmosphere, the way we lift because of all the history here . . . I can understand why rival players don’t find any of that ideal.” (Walshaw, 2014) For these same teams, in the period between 2001 and 2012, our results show that Manly has a 66.67% win percentage at a traditional Sydney stadium against a team from Sydney, the West Tigers have a 62% win percentage at a traditional Sydney stadium when playing a team from outside Sydney, and St George Illawarra have a 72.13% win percentage at a traditional Sydney stadium against a team from Sydney. **Note that the strength of the impact seems strongest for the West Tigers who have an home win percentage across all stadium types of 53.10% and are rated as the 11th most successful team, in comparison to Manly with 65.28% and listed as the 2nd most successful team or St George Illawarra with 64.29% and listed as the 3rd most successful team at home between 2001 and 2012.**_

 

[tom620]

Seems to support the case for not moving to ANZ full time…

Over time teams are having more success at ANZ, but generally this is against teams that share the stadium. The Traditional Sydney Stadiums have a stronger home advantage.
It goes to show that the financial stability issue of getting a guaranteed windfall from playing at ANZ is a big deal.

Figure 2 on page 9 of this paper, http://www.feem.it/userfiles/attach/2014521129524NDL2014-053.pdf, shows how the probabilities have differed over time.

 

[mremedy]

You have reported probabilities of wins per home ground type and opponent, however the probabilities are very close to each other. Did you do any analysis to see if the results are statistically significant?

 

[innsaneink]

TLDRCBF

 

[cqtiger]

TLDRCBF

What Ink said

_Posted using RoarFEED V.4_

 

[tom620]

You have reported probabilities of wins per home ground type and opponent, however the probabilities are very close to each other. Did you do any analysis to see if the results are statistically significant?

Good question. The differences are statistically significant, but I haven't highlighted this too much as I see the differences as being numerically significant.

Controlling for team quality (via the incorporation of the number of competition points and the for and against before each match, plus the number of wins that a team has had in the finals during the whole period) was sure to reduce the probabilities in comparison to win percentages and also bring them closer together.

And while the probabilities are relatively close together, after controlling for a range of factors and holding these factors constant, a few percentage points related to home advantage is quite significant/important.

I have shown the averages for the whole period here, but the 2012 numbers or the individual years (shown in Figure 2 on page 9 of this paper, http://www.feem.it/userfiles/attach/201 … 14-053.pdf ) do show larger differences.

Thanks for the question.

 

[tom620]


Here is the Figure that I keep referring to.

Should cut to the chase and show some of the differences across years.