NRL Betting tips: How important is home advantage?
It makes sense that NRL teams perform better at home than away. Familiarity with your own turf, home crowd support and not having to travel are three obvious factors in favour of the home team, as well as the extra ounce of effort that comes with not wanting to embarrass yourself in front of your home crowd.
So how big is the home advantage in NRL?
Looking at my records for the last couple of seasons, the Home team put an average of 22.3 points on the board and the Away team averaged 19.0 points. Let’s round that to a 3 point estimated advantage.
Interesting, but what does 3 points translate to in terms of a probability advantage?
Below are Opening Odds on a team in an NRL fixture and also a typical line that Pinnacle put up during a season. It isn’t always that figure for the line, but it is within 1 or 2 points.
Typical Opening Line (points spread)
-2.5 to 2.5
-2.5 to 2.5
Assuming Pinnacle know what they are doing (and their record as one of the biggest low-margin bookies in the world would suggest they do), between odds of $1.40 and $1.70 the opening line points are moving in increments of 1.5 points, which is handy if we are dealing with a 3 point advantage here. If we use $1.60 to $1.50 to represent a 1.5 point move complemented by an opposing team’s probable movement from $2.40 to $2.60 then we have in total moved 3 points.
$1.60 to $1.50 represents a 6.7% improvement in probability and $2.40 to $2.60 represents a 7.7% diminishment in probability. Taking the middle ground at 7%, if you are assessing each team’s probability of winning without looking at where the game is to be played, you would then adjust the final probability assessments by plus 7% (Home), or minus 7% (Away), (i.e. multiply the Home probability figure by 1.07 and Away by 0.93 respectively) when you note the fixture’s location. That would seem to work approximately in all but extremely divergent team skill situations. Now that gives an indication of the advantage in an overall sense, keen fans will have their own opinions on which teams are exceptionally strong on their home turf and can adjust their probability assessments accordingly. Serious NRL betting tips, analysts and models factor in kilometres travelled, time differences, start times and weather conditions to some degree.
Playing with data from the 2013 through 2016 seasons I was looking for where Pinnacle may be weak in their pricing for the line or fixed odds.
The following chart shows what you would have achieved betting the opening fixed odds on home teams paying in the range $1.25 to $1.40. It is 123 bets of 800 games and you would have made 9 units profit, a 7.5% POT, not bad for simple betting although the usual backfitting and small sample size caveats apply.
However, stray over $1.40 and profits plummet.