A previous article published by The Roar detailed predictions for the 2015 Rugby World Cup before the tournament began.
This article provides updated World Cup estimates after the completion of the pool stage of the tournament. As in the previous article, the estimates are generated using the rugbyvision.com global rankings to predict score margins and simulating remaining games, while accounting for uncertainty in expected match outcomes.
The scheme is an Elo-type system tailored to international rugby matches and differs from the system used for the official World Rugby rankings. During the pool stage of the Cup, the system correctly predicted the winner in 34 of the 40 matches – an 85% success rate – and the average difference between the predicted score margin and the actual score margin was 11.3 points per game.
This performance compares favourably with the prediction accuracy of bookmakers. Like the rugbyvision.com predictions, the bookmakers’ favourite won 85% of matches, but the average error in the bookmakers’ spread (also known as the line) was 13.6 points per game.
The rugbyvision.com system also predicted seven out of the eight quarterfinalists correctly and projected the right quarterfinal seedings for all teams except those in Pool A. For this pool, the system (incorrectly) predicted that England would top the group followed by Australia.
Our rating points for teams that qualified for the quarterfinal are presented in the table below.
Differences in rating points equal expected score margins in a game between two teams. For example, in the quarterfinal between New Zealand and France, New Zealand is expected to win by 16.4 (128.3 – 111.9) points, or 16 points when rounded to the nearest whole point.
However, this prediction represents an average score around a distribution of possible outcomes, some of which involve a larger or smaller victory for the All Blacks, and some are associated with France winning. According to the model, France has a 12.9% chance of beating the New Zealand.
Using the rating points and simulating the Rugby World Cup while accounting for outcome uncertainty facilitates estimation of the probabilities of each quarterfinalist reaching future milestones in the tournament, which are presented in the figure below and in the table.
New Zealand is the most likely team to win the RWC with a 44.8% chance of retaining the trophy. In our pre-RWC estimates, England were second favourites with an 21.8% chance of winning the tournament.
The big winners from England’s failure to make the quarterfinals are Australia, who are on the opposite side of the playoff draw to New Zealand and South Africa, and have a 25.2% chance of winning the tournament, up from 8% before the Cup started.
South Africa are third favourites with a 15.4% probability of being crowned champions followed by Ireland with a 9.5% chance. France and Wales have relatively low expected chances of lifting the Webb Ellis Cup as they are on the same side of the draw as New Zealand and South Africa.
Aggregating by hemisphere, there is 86.9% chance that a team from the Southern Hemisphere will win the RWC.
Further simulations also indicate that there is a 60.7% chance that the final will be between two teams from south of the equator, a 35.8% chance that there will be one Northern and one Southern Hemisphere team in the final, and only a 3.5% probability of an all Northern Hemisphere final.
Who will win the Rugby World Cup? No team has more than a 50% chance of lifting the Webb Ellis Cup, but statistics suggest that there is nearly a nine-out-of-ten chance that it will be a team from the Southern Hemisphere.
Find the most recent Rugby World Cup probabilities and global rating points at www.rugbyvision.com. Join in the analysis and discussion at www.facebook.com/rugbypredictions and on Twitter by following @rugbyvision. Rugby Vision will also make live, minute-by-minute predictions for key RWC games.
Join The Roar rugby editor Christy Doran, former Wallaby Matt Toomua and a cast of regular and special guests as they look at the biggest issues in the game on The Roar Rugby Podcast. If you’re looking for great odds on the next game check out Aussie bookmaker PlayUp. Chances are you’re about to lose. Set a deposit limit.
Seven months after the Springboks sensationally elected for a scrum from a mark inside their 22-metre line during their run to a fourth Webb…
Column: So, elite test rugby might be going to Qatar. Interesting. I can’t say I’m too enthused. Nothing to do with sportswashing, but we’ll…
Australian rugby has many problems - financial crisis, ever-shrinking audiences, shortage of coaching expertise, Greg Martin, etc etc. But one problem which I have…
By my count, the Brumbies have played three teams of consequence this season. The first two - the Chiefs and Blues - thrashed them…
Chiefs coach Clayton McMillan says it’s “purely coincidental” that Semipeni Finau has put on a massive, late hit on a fourth fly-half in nine…
He was born 1905, 1904 or 1908 according to various reports, in Wairoa, Hawkes Bay, and is remembered as one of the great Māori players.
