Update: If this is a chess.com tournament grouping, I really haven't a clue.
However => If you are referring to an actual USCF tournament, then the pairings tend to be mostly Swiss style.
To summarize (with maximum simplicity :) )
1. Let's say 8 players play an event, all rated in descending order from no. 1 through 8.
2. The TD uses a software that automatically pairs them in accordance to a ratings bracket similar to other sports like Tennis. Almost always, the top player plays somebody in the middle and you keep going down the list. It usually goes like this.
- 1 vs. 5.
- 2 vs. 6.
- 3 vs. 7.
- 4 vs. 8.
3. After the first round, let's assume "predictable" results ( better rated wins), so the winners are: 1, 2, 3, 4. The loser group is 5,6,7,8.
4. Now for the next round, we want to divide the group in terms of their "total" score. So the winners form one pool (scored 1 point) and the losers another.
The pairing is done in a similar manner as shown in 2. 1,2,3,4 are arranged in desc. order of their rating and once again paired.
- 1. vs 3.
- 2. vs 4.
Similarly, the "loser" group:
- 5 vs. 6
- 7 vs. 8.
This is a simplistic example of the "Swiss" system of pairing.
5. Things get tricky for the next round. You'll have people who have scores of 2.0, 1.5, 1.0, 0.5 and 0.0.
I believe that first round selection is random within a ratings range, or else based on a player's entry position. Not sure which it is. But what about subsequent groupings? Do tournament directors match players based on their ratings, or are the groups again determined by chance? Thanks.
(I couldn't find an answer to this either in the "Help" files or in the forums.)