Saturday, May 9, 2009

Rating System for Turnabout

If something is popular, it is good to determine how proficient people are at it. This is the reasoning behind developing a rating system, so that there is a record of who is doing well at any given moment.

When it comes to Turnabout's rating system, it does not work well with an ELO-based rating that rises and falls based on match wins. Unlike standard Magic: the Gathering events, the match scoring system awards points based not just on the match win, but on the degree of that win. A person can win one match 30-0, lose the next one 12-18, but those 42 Victory points will still be more than the person who wins two matches 20-10. Given the nature of the event, it makes sense, for the first player has likely won 3 games out of 4, whereas the second player is likely to have only won two. The match win is often less important than earning enough Victory Points to secure a particular position.

This dynamic forces the rating system to acknowledge two separate factors: the number of matches won and the final placement of the players. To deal with these factors, each is given an individual rating, and these factors are multiplied together to determine the overall award for the event.

Match Wins
The number of matches won is easy enough to determine. For the purposes of this rating system, it is often beneficial to keep players involved in the event as long as possible. So toward that end, the system rewards players who play all scheduled rounds as having won an extra match. Thus a person who goes 1-3 in a four-round event would be counted as having two match wins; if the event were five rounds and the person dropped before the fifth round, only one match win would be recorded. Draws are counted as half a match win.

As has been mentioned before, Turnabout does not normally use any of the elimination formats, but for those, playing all scheduled rounds equates to playing until eliminated. Those who are eliminated naturally receive the bonus match win, while those who drop before being eliminated do not.

Final Position
This rating is determined based on a formula that guarantees that each match win will be worth at least one point, and that those who finish well will receive a better multiplier than those who do not. It is recommended that no event have fewer than four players, and these values will assume that there are at least four.

Number of Players

Multiplier for First Place

Position of Player

Modifier to Multiplier





















Each doubling


Each doubling

Additional -1


So a person finishing 5th in an event with 16 players would get 3 points per match win (6 for 16 players, minus 3 for 5th place), as would a person finishing 64th in an event with 100 players (9 for 100 players, minus 6 for 64th place).