RWC 1987 – 2011: did Form and Tradition matter ?

In the run-in to RWC 2015 this week, there have been many reasons suggested as to what factors might determine on-field success. There have been some differing opinions about the role of Form and Tradition.

Our research on RWC 1987 – 2011 suggests that Form mattered, albeit in subtly different ways. We looked at two measures of form: a) Rankings, and b) Win Percentage; using input data. We found that both variables were positive indicators of how far a team would progress in the tournament. In particular, we found that on average, the higher ranked team won the final.

We have previously posted that Tradition (as measured by the number of years a nation had played the game) was also a positive indicator of success.

So our conclusion would be that in the past, both Form and Tradition have mattered. So why then have there been differing opinions ? It may be due to the subtlety we found, i.e. that Form mattered, but depending on the measure and the stage of the tournament.

To expand, it is widely believed in sports that recent form can be an important indicator of a team’s short-term prospects. The approach we took to test this was to see if Rankings and Win Percentage (latter as measured over the four year window prior to each RWC) could on average explain subsequent success in that RWC.

We could not find any effect of Ranking in the early stages of the tournament – which again does not mean that it was definitively un-important, it just means that we could not find an effect. Interestingly though, we did find a positive effect at the final stage. On average, the team with the higher Ranking won the final and so became champion. Of the seventeen variables we considered overall, we found that only six were influential in terms of becoming Champion or the runner-up. Ranking was one of those measures.

The Win Percentage (measured over the four years prior to each RWC) was a positive indicator of teams who would progress from the quarter-final to the semi-final. We did not find it had an effect at any other stage of the tournament. Why that would be so, one can only ponder. It could be that the gap between teams at the quarter-final stage is still relatively wide – bearing in mind that pool winners play pool runners-up. There may for example have been key injuries during the pool stages, so that teams with a higher Win Percentage then have stronger reserves to call on at that stage.

As mentioned above, we have previously posted that we found that Tradition was a persistent indicator of progression at each stage of the tournament. Of all the variables we considered, it was the only one that showed an effect at each stage of the tournament.

So all in all, we conclude that form and tradition did matter in past RWCs. We would re-iterate previous cautions about the limitations of small sample size. It is not un-reasonable, however, to imagine that both might be subtly influential in RWC 2015.

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Empirical Rugby

Empirical Rugby is a blog that provides fundmental insight into rugby union using empirical analysis of rugby data.

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