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Points and Percentages: Another reason why SANFL is better |
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Tuesday, 12 May 2009 15:32 |
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The purpose of this article is partly to head off those annoying questions I hear down at the pub:
"Why doesn't the SANFL calculate their percentage like the AFL?"
"Why doesn't the SANFL give 4 points for a win like the AFL?"
And here's an actual quote from someone on an AFL footy forum who was struggling with the SANFL system:
"It seems to me, it's just being different for the sake of being different. Is there an actual purpose?"
To begin, let's take a look at the percentage systems.
The AFL 'percentage' system is just a simple quotient of one team's score over another: For/Against x 100.
The SANFL percentage system is a true percentage system. It shows what percentage a team's score is of the aggregate score: For/(For + Against) x 100.
Example:
Let's say Team A scored 125 points, beating Team B who scored 75 points:
Team A's AFL percentage would be:
= 125/75 x 100
= 166.67%
Team A's SANFL percentage would be:
= 125/(125 + 75) x 100
= 62.50%
Perhaps the most obvious fault with the AFL system is the fact that it generates so-called percentages greater than 100. We are accustomed to seeing percentages in the range of 0 to 100 since 'Percent' means 'per 100'. Cast your mind back to what we were all taught in Primary School. The SANFL formula guarantees that each team's percentage will be in the 0 to 100 range. ie. a true percentage.
Both systems give you an indication of how dominant a team is. In the above example, by the SANFL system we see that Team A did 62.50% of the scoring in that game. By the AFL system we see that Team A scored 166.67% of what Team B scored. It's subjective, but I would argue that the SANFL system provides a simpler and more useful analysis.
Ultimately, the SANFL percentage system is mathematically sound, but the AFL system is not. The AFL system doesn't work if a team fails to score: you can't divide by zero. And that IS a remote possibility, even at SANFL/AFL level.
Now that we have completely discredited the AFL percentage system and proven beyond doubt that the SANFL percentage system is better and correct, let's turn our attention to the points systems.
The SANFL awards 2 points for a win and 1 point for a draw. It can't get any simpler than that. Why would any competition deviate from this? A good question, because that's exactly what the AFL has done.
Inexplicably, the AFL awards 4 points for a win and 2 points for a draw. Heck, why not 6 points for a win and 3 points for a draw? Or perhaps 12 and 6!? There are sporting competitions that award bonus points for large wins, or award more points for a win to reward attacking play (eg. Soccer awards 3 points for a win and 1 point for a draw), but none of these valid reasons apply to the AFL.
Another (albeit minor) reason to like the SANFL points system is it's easy to spot teams that have had a draw - they've got an uneven number of points (unless they've drawn an even number of times).
So there you have it. Further proof that SANFL footy is better! |