We are announcing the calculation of a new pool metric: Plus / Minus (+/-). A similar metric exists in the game of hockey where a player gets a +1 whenever their team scores while that player is on the ice; and receives a -1 whenever the opponent team scores while that player is on the ice. We’ve adapted this to the game of pool in a slightly different manner.
Suppose you are playing 9-ball and you hit in the 4 ball on the break, and then go on to pot the 1 and 2 thereafter, but miss the 3. From there you opponent cleans up the rack. In this scenario, your Plus / Minus = -6, while your opponent’s PM = 6. This is because you potted three balls and left 6 on the table before your opponent cleaned-up.
After all your matches have been recorded, we take the summation of these game values and record it in an overall stat we call Plus / Minus (+/-). Naturally, a player always wants to be > 0, and never < 0. The players with the highest (+/-) can be said to clean up well and often against their opponents. The same works conversely for the players with the lowest (+/-).
It’s a simple metric, but it does provide insight into how well a player plays against their opponent, and ranks them accordingly to other players.
Below you’ll find the (+/-) values for the games we have thus recorded, along with total number of data points for this stat. It is a rule of thumb that for any stat to be considered significant to prediction, that the total number of data points should be greater than 30. Stay tuned as we record more matches and obtain more users using our software. So, check back often to the link provided at the beginning of this press release to stay up-to-date with the current Plus / Minus rankings.