When golfers can move in and out of the number one slot of the world rankings and Ireland’s rugby team can bounce from 2nd to 6th in a matter of weeks, it was time for a column on rankings system. Just don’t ignore them.

From the Irish Times of Wednesday, September 9th, 2015.

Who is the best? Well, it’s complicated. Rory McIlroy will return to the top of golf’s rankings next week without playing a stroke. Ireland’s rugby team recently soared to second in the World Rugby rankings, plummeting to sixth just weeks later. Welsh footballers reached the top ten of Fifa’s rankings for the first time. A great achievement, but how do we know what all these ranking systems really mean?

Chess has long had a system to rate players. The Elo rating system, named after its creator Professor Arpad Elo, is based on two parties completing a contest against each other after which the winner takes points from the loser. The amount of points transferred between the players depends on their own rankings going into the contest, with an underdog winning being awarded more points than a victory by a heavy favourite.

Many rankings systems are derivations of Elo’s work, with details changing such as weightings to take into account home advantage, for example, or certain tournaments defined as being especially important.

There isn’t even agreement on the best way to run a tournament in team sports. America likes to package its sports entertainment monopolies into smaller divisions leading to the hype of the play-offs. European club football prefers to reward the marathon of the season-long league, not simply a well-timed finishing sprint. But football has its cups too, at least when they don’t get in the way of European competition (which comes, as it happens, in the shape of a hybrid league/cup).

Rugby union’s top level club competitions can’t even agree on the best way to run a bonus point system, while at international level the Six Nations rejects the notion entirely.

Where world rankings are concerned it’s a similar story. Take a simple thing; the amount of time taken into account to produce a player or team rating. Tennis rankings produced by the ATP are done over a rolling one year period. For golf it’s a rolling two years, hence the current flip-flopping of Rory McIlroy and Jordan Speith that seems so incongruous with current results.

Read more: http://www.irishtimes.com/sport/numbers-game-ranking-systems-it-s-complicated-1.2344847