Past RWCs: did ‘playing tradition’ matter ?

It has frequently been suggested that ‘playing tradition’ (which is not easy to define) was a crucial source of success in past Rugby World Cups. We decided to put this notion to an empirical test.  The proxy we used was the number of years elapsed since a nation had made its international rugby debut, in other words, its playing ‘longevity’.

So what did we find ? One feature of rugby union – that may be somewhat particular to the sport –  is that there is a clear linkage between the date of a nation’s international debut and its international ranking (see this international rankings chart ).  We analysed past RWC data (from ESPNscrum.com) and found that having made a more recent debut had a negative effect on a country’s prospects of advancing through any past stage of RWC.  Put more loosely, longevity of playing the game has mattered in all RWCs played to date.  In general, teams with a longer playing ‘tradition’ advanced farther.   Of all the variables we have looked at, this is the only one that had an effect at all stages of the tournament.

To add some more detail: the Rugby Football Union  was founded in 1871, followed by Scotland in 1873, Ireland in 1879, and Wales in 1880 (see RFU History).

The first international game was played in March 1871 between England and Scotland.  It was a 20 a side run-out, won by the Scots (see this ESPN link for details).  In terms of longevity, that would give those two playing nations a 144 year head start against a hypothetical international team, if it were to start play this year.  That is of course an extreme example, given that World Rugby already has 120 member unions, many of whom have been playing the game for decades.

In this international rankings chart , we plot the year a country began playing rugby against its international ranking (the rankings data is for 2014 but is unlikely to have changed too much in the meantime for our purposes here).

The red line of best fit (or ‘regression line’) is clearly sloping downwards.  What this means is that countries  that were newer to rugby – shown as one moves to the right in the chart – tended to achieve lower ranking scores.  Conversely, the highest ranking nations tended to be the ones who have been playing the game the longest (look at the upper left positioning of tier one nations such as New Zealand).

So in that sense, the first shall be first (at least in international ranking terms).

We are not at all suggesting that longevity is the only reason for this, but we have run an empirical model to test the theory.  Holding other factors constant (‘ceteris paribus‘), we can say with a high degree of confidence that in a statistical sense, on average, increasing the length of time a country has been playing the game, would positively affect its international ranking score.

We also tested for this in the context of past RWCs.  The table below is a re-cap of the finalists so far.  Now cross check the nations in this list against the graph, and we see that they have typically been playing the game for a very long time.

TABLE: PAST RWC FINALISTS

RWC Winner Runner-up
2011 New Zealand France
2007 South Africa England
2003 England Australia
1999 Australia France
1995 South Africa New Zealand
1991 Australia England
1987 New Zealand France

In terms of our formal empirical tests, we found that in past RWCs, the ONLY variable that we looked at that had a consistent – i.e. at all stages of the tournament – effect on advancing was how recently a country had made its rugby debut (stated this way the relationship is negative, i.e. a recent debut was a negative indicator).

Note 1: from an international policy-making perspective, we’re not suggesting that this is new information, neither are we making policy recommendations.  What we would highlight to readers though is the ceteris paribus dimension above….the longevity / rankings relationship can only be expected to diminish if other factors are not held equal, e.g. through investment in talent development internationally.  Generating the funding for same is basically the economic raison d’être of the RWC, which in a sense nicely links RWC to the game’s future development.

Note 2: h/t to Charles Dainoff for his original article here Why-Some-Nations-Are-Better-At-Rugby-Than-Others that got us thinking about this area.

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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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