Respect to Ali W, but we prefer a different approach

This Article by former All Black Ali Williams got us thinking. The gist is that New Zealand won the RWC in 2011 because they had a core of experienced players who were battle hardened from previous RWCs.

There is no argument per se with the idea that New Zealand could improve over time. The thinking, however, raises an important question, and we think probably misses out on a key point.  The reason is that that approach compares what econometricians (aka economic statisticians or empirical economists) call within subjects, i.e. comparing the All Blacks teams of 2003, 2007, and 2011.

The key point though is that whilst those groups may have advanced, we think its much more insightful to compare ‘between‘ groups, i.e. New Zealand vs France, New Zealand vs Scotland etc, ideally at each point in time.

To illuminate, imagine a bizarre hypothetical counter-factual.  In 1995, suppose that only 1 team in the world turned professional, had access to vast resources, the best coaches, superb training facilities, and was allowed to recruit good players.  But in 1995, they started out well behind the others.  By 2015 though, if everyone else was still in the amateur era – a sort of ‘steady state’ – it wouldn’t be hard to imagine that this hypothetical team had progressed hugely to become a world leader.  They had improved, and everyone else had stood still.  So not only was their 2015 vintage better than their 1995 vintage (within progression vs themselves), but by 2015, it was better than everyone else (between progression).

This relates to the previous post on RWC design.  During each edition of RWC, teams play against each others current vintage, i.e. Scotland 2011 does not play Scotland 1999.  So the fact that Scotland 2011 may or may not have been a better team than in 1999 is not what really counts.  What really counts is how Scotland perform relative to say France or Wales if they play each other in head to head contests.  France’s 2011 vintage may also have been much better than their 1999 counterparts.

So we think it is more insightful to focus on relative differences between teams (subjects).    The fact that the All Blacks won RWC 2011 would suggest that they have been progressing at least as fast as everyone else over time, and possibly even faster.  The maintenance of that relative gap is what really matters.

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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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