Accelerated Pairings

Note: The text that follows is paraphrased from the WinTD by Estima Software help file. 

The currently suggested method for club TDs to use is Variation 28R2 as specified by the USCF.  The WinTD options that will produce this are the "Standard Accelerated" and Not using the +1 selection.
Accelerated pairings alter the basic rules of Swiss System pairing in the first two rounds in an attempt to quickly reduce the number of perfect scores. Through the Add/Edit a Section Dialog Box you can request accelerated pairings for a section, using any of three possible systems. The default setting is "Standard Swiss": pairings are not accelerated.

The choices (provided by WinTD) for accelerated pairings are Standard Accelerated, 1/6's Accelerated, and All Rounds Accelerated.

Standard Accelerated

If you choose the Standard Accelerated method, Windows TD does the following:

Round 1:
Players are divided into four (roughly equally-sized) groups from highest ranking to lowest. Call them A1,A2,B1 and B2 from top to bottom. Group A1 plays A2, B1 plays B2. With normal pairings, A1 would be playing B1 and A2 would be playing B2. Thus the stronger players (in A1 and A2) will have tougher competition in the first round under accelerated pairings, the weaker players (B1 and B2) will have easier games. In effect, the first round pairings are more like typical second round pairings.

Round 2:
Winners from A1 versus A2 play each other. Non-winners from A1 versus A2 play winners from B1 versus B2. Non-winners from B1 versus B2 are paired normally (draws play draws, losers play losers - this is slightly different from the version in the rulebook, where the draws and losers in the last group are pooled - there seems little point in that).

Accelerated pairings work to reduce the number of perfect scores faster than normal pairings if the non-winners from A1-A2 win most of their games against the B1-B2 winners. If the B1-B2 winners take a fairly high percentage of games off the A1-A2 non-winners, accelerated pairings will produce more perfect scores, not fewer.

This implementation of accelerated pairings follows USCF Variation 28R2.  Note that this method is different from the way that programs such as SwisSys and PairPlus do accelerated pairings. They follow Variation 28R1. The two methods differ in the second round handling of A1-A2 draws. Windows TD pairs them against B1-B2 winners. Under Variation 28R1, they play each other. The Windows TD method is better for reducing the number of perfect scores.

However, if you want to use the 28R1 (added-scores) method, check the +1 Accelerator box in the Pairing Rules section of the Preferences dialog box.

WinTD chooses the break point between the A’s and B’s by rounding up to an even number of players in A. For instance, with 66 players, WinTD will put 34 in A and 32 in B. If you want a different break point, you can check the Input Accelerate Break box in the Pairing Rules section of the Preferences dialog box. With this on, you will be prompted for the break point when a round is paired. (A separate box pops up after the Pair a Round Dialog Box).

1/6's Accelerated

The 1/6's Accelerated choice follows USCF Variation 28R3. Please consult the USCF rules for details on these Variations R1, R2, and R3.

The USCF recommends using accelerated pairings if

     1) the number of participants is more than 2 to the power of (number of rounds plus one).

     2) there is a large difference in playing ability between the strongest and the weaker players. They make little sense where the difference between the top and bottom half is only 100 rating points or less.

We would recommend one additional requirement: that the ratings of the players fairly represent their skill level. It is much more likely that they will fail to reduce the number of perfect scores if there is a high percentage of unrated or provisionally rated players.

All Rounds Accelerated

The final choice in this is to "accelerate" All Rounds. This NEVER should be used in a real tournament. It distorts the pairings all the way through the tournament, giving the stronger players tougher games and the weaker players easier games. Use this only for warm-up tournaments where your goal is to give appropriate competition to everyone, and scores and prizes are of little concern.