When using accelerated pairings in a tournament, aren’t they supposed to be used for the first 2 rounds of a tournament and not for the first round only?
Ken,
The rules are fairly self-explanatory on this point, and even the title of the rule suggests the answer:
28R. Accelerated pairings in the first two rounds.
…
For the third and subsequent rounds, the temporary rating adjustments are ignored and the pairings are made according to the basic system.
Accelerated pairings are supposed to give the equivalent of one additional round, but that benefit really only accrues to players at the top of the standings.
My one experience with an accelerated pairings event as a player was not an enjoyable one, I won my first two rounds (as a 1400 player well below the break) and then got stuck with the defending state champion in round 3 on one of the top boards.
I got crushed.
It seems like lower rated players don’t get much benefit from accelerated pairings. One round acceleration seems even worse.
One case immediately comes to mind as a justification for only doing accelerated parings in round one. If there are enough players entering during the first round then it may be preferable to split the section into two with prizes for each one. In that case the accelerated round one pairings are valid normal Swiss pairings for each of the two sections.
For larger non-US-Chess-rated fixed board team tournaments with weighted boards that make ties unlikely I have done a partial acceleration in round three of a four-round event if there are six 2-0 teams with exactly two from the lower rating bands. Those two are paired against the top two 1-1 teams and the remaining four winnow down to a single 4-0 team. I’ve only done it when there are 40+ teams and four rounds.
What do you do if your software allows accelerated pairings for Round 1 only?
The benefit really can only accrue to players at the top of the standings, since the goal is only to try and avoid multiple perfect scores and have the top contenders have a better chance of facing each other.
I note that absent accelerated pairings you might have faced that defending state champion in round 1, which isn’t an improvement. Fundamentally, a section spanning around 1000 rating points is never going to be great.
I find software that works. What software are you dealing with?
I’m guessing Ken is using Chess Nut. If so, he caught us in the middle of an update to that feature where we are moving it to the section settings from the pairing button. If that is right Ken, can you give it an hour while this gets finished? Sorry for the inconvenience
ngl5000. . .Thanks for the information.
Actually, it has the same effect at the bottom as at the top (theoretically). If all results are W-L, then standard accelerated pairings will give you 1/8 at 2-0, 3/4 at 1-1 and 1/8 at 0-2 while standard pairings will be 1/4 at 2-0, 1/2 at 1-1 and 1/4 at 0-2, so it should produce fewer oh-for-the-tournament. (As Mike Zacate would explain, you earned the right to get crushed by starting 2-0 rather than getting crushed right off the bat).
"One round’ of accelerated pairings basically just switches rounds 1 and 2 with no real benefit to anyone.
The point of accelerated pairings under US Chess rules is to (in theory) reduce the number of perfect scores. It can fail miserably if the bottom half R1 winners win more than half their games vs the top half R1 losers (you could then end up with more perfect scores, not fewer). You’re not really supposed to use it unless there is a rather substantial spread in the ratings.
The standard FIDE acceleration jimmies the pairings through the first half of the tournament (5 rounds in a 9 round), but throttles back the adjustment from 1 point to 0.5 points after half of the acceleration period. I assume someone did some simulations which showed that that improved the rank correlation of ratings with results, though probably with a section roster which more closely resembles big international opens rather than small one-section Swisses. In a 9 round international open, they don’t have to worry about perfect scores since the winner’s score is likely no higher than 8.0.
We modified a 1v2 section of 8 players to accelerate the 1st round 1-3 4-2 5-7 8-6 then switching to a regular 1v2 for round 2. I could not figure out how to do the switch as the accelerate was locked in for round two (swiss sys) 
That’s probably a better way of handling it than 1 vs 2 and 3 vs 4 in round one.
A one-round acceleration mostly just pushes the likely first round matchups to round 2 (first round upset wins and draws notwithstanding).
I’m a bit confused about what you were trying to do. That sounds like it would give you 1-2, 3-4 pairings but with rounds 1 and 2 reversed.