Automatic Handicap Systems
Scottish croquet players playing in "serious" games are expected to keep a handicap card in which the results of qualifying games are recorded. There is a full definition of qualifying games in the document below, but essentially any game from an internal club competition upwards counts. The handicap system is an automatic system in which the winner of a game will gain index points and the loser will lose the same number of points. For handicap games, there are normally 10 points exchanged. For level games the number of points exchanged will depend on the handicaps of the two players: a high handicap player beating a low handicap (better) player will gain between 11 and 19 points, whereas if they lose they will only lose between 1 and 9 points.
There is a trigger point associated with each handicap and when, at the end of a day's play, your index is at or past the trigger point for the next handicap number up or down, your handicap will automatically change. For high handicaps the trigger points are 50 index points apart, so winning 5 handicap games in a row will reduce your handicap by one notch, assuming your index started at the trigger point associated with the old handicap. Note that if you just get past the trigger point and your handicap is reduced from, say, 24 to 22, and then you start losing games, you don't go back to 24 until you have lost enough games to take you to or past the trigger point for 24. In other words, it's not possible to keep switching between 24 and 22 if you were to lose every other game.
Club and SCA handicappers have the power to intervene and set handicaps manually. This is typically used for rapid improvers when the automatic system cannot keep up with their rate of improvement, or for players who return to the game after a period of absence.
For a full description of the SCA's automatic handicapping system, please see the document below.