Wednesday, January 4, 2012

Tournament Scoring: Weighting & Normalisation

It's common in battle point tournaments for a player to receive a score in several categories - usually a subset of battle, comp, painting and sportsmanship. These scores are then added together to provide an overall score.

But while this method seems intuitive, it can result in some categories having an unexpectedly stronger or weaker influence on the final rankings. When combining tournament scores from multiple categories one should not just add them together without thought. There is more to it than that if you want to produce a meaningful and competitive result.

Almost always the scores added will be weighted according to the preferences of the TO. As an example for this article, Best General might consist of 50% Battle, 20% Comp, 20% Painting and 10% Sports. This allows minor scores to contribute without overshadowing other more important scores. The choice of weighting helps define a tournament's focus - and may even influence who turns up.

Note that in some cases the scores will have been contrived so that they are weighted automatically - in the above example, you could make the Comp and Painting a score out of 20, and the Sports out of 10. This is a good idea in most cases as it helps to simplify the scoring process and makes the whole thing more transparent.

Unfortunately the raw weights, like those my example, can be very misleading. The problem is that in many cases there is a portion of the score that anyone can achieve without competing or applying effort. These points are basically distributed to every competitor by default, so the only effect they have is to lessen the impact of the associated category on the overall score - and punish those who cant read or be bothered. Here in Australia 5 points is often awarded for a loss, and 20 for a perfect win. This means that battle points are only 75% as important as at first glance (you can remove 25% from everyone's scores)

To go one step further, imagine a 20% weight for a Painting score that consists of a checklist of simple tasks. What if as long as everything is painted three colours and based then you get 15/20 - almost everyone gets that right? In a competitive sense only the remaining quarter of your score actually matters, so the actual competitive contribution of Painting to the overall score is 5%.

You should compare these adjusted percentages if you want to really understand their contribution to your final score. Let's do so for my example: Battle might contribute 37.5%, Comp 16% (it's a 1-5 score x 4), Painting 5% and Sports ~3% (very rare to get anything other than 4/5). So, before you pick up the brush to add additional highlights, it might be wise to spend some more time softening your army list!

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