Lots of factors for sure, but given the paucity of data made available by the RFL (and that for fantasy league purposes, not informing the public) this is what we have.
On home wins v away:
Championship this year:
61%
Championship since 2006:
55%
SL this year:
55%
SL since 1996:
56%
The big four in the US
NBA Basketball: 62% (many more games than RL, and the crowd is right on top of you)
MLB Baseball: 54% (many, many more games than RL)
NFL: 53%
Ice Hockey: 55%
I don't have data for soccer but I understand from a bit of research last night that it's about 63% in the Premier League.
We're in the same ball park as other major sports.
Because I was curious though (I'm a very curious person) I decided to look in to penalty counts. I only have that data in the SL, and only from 2007 onwards.
Several problems with this data. It's raw penalty counts overall for one thing. There is not context associated with it at all. We don't know when the penalties were awarded, what for, what the score was at the time or anything like that. All of that would be very useful to know. (I have started stealing the data from the disciplinary site though, so I may be able to add *some* context on how "dirty" a game overall it was once I get that into a shape I can work with).
There is also nothing here about penalties that should have been but were not, errors spotted or missed, etc. It's not a complete picture, but it is still in my view a revealing picture.
Anyhow, on with the show. There's a slight change with this table in that HomeConc refers to penalties conceded by the home side. AwayConc is similarly those conceded by the away side. This isn't penalties 'won', which is typically how we refer to them. The final column shows the average number of penalties that are in the home side's favour.
There is, even amongst the best referees we have, a tendency for the home side to win the penalty count.
But if we assume, and I agree that it's an assumption that this is the cause, that the home crowd has an effect on the referee's performance then it also makes sense to look at the degree to which that happens amongst different teams. Different grounds, different ways sound echoes around the place, the sophisticated and cultured nature of some team's fans (Bradford, for example) compared to the uncouth, slavering at the mouth vernacular swearitude of others (Leeds, say).
This one is how much teams benefit from the referee by being at home:
And straight away we see that those teams with the smaller crowds, who may even be often outnumbered while at home, benefit the least from the referee. RFL bias against smaller teams? We've thought that at one time or other but I don't believe it. Interesting teams at the top though, right? I certainly wouldn't have predicted those.
What if we flip that on its head and see which teams are at the biggest disadvantage on the penalty count away from home:
Again, Crusaders and Salford. Do we say that these are the two dirtiest teams in Super League since 2007? Because I absolutely do not believe that. And there's Catalans. Quite the advantage at home and nailed to a tree as an example to others away from home. That's what you get when most of your away support are hipsters from Leeds who pretend to be French at weekends.
I think a good number of SL fans would predict that Wigan would be the side who should be penalised the most. Whether by false impression or not it's hard to say, but I think they are probably the most complained about in terms of 'gamesmanship' and the extent to which they walk the line in the tackle. Solidly mid table both away and at home though.
Large home crowds, large travelling support. Same for Leeds (albeit less commonly thought of as an edgy team). Does it explain the difference?
That's up to you. I think so though.
(Apologies for the long post. And apologies for the odd colours too - I don't actually know what I'm doing).