The USCF rating system as described by Professor Glickman includes a factor called
If m < 3, or if the player competes against any opponent more than twice, the "standard" rating formula that results in Rs is given by
Rs = R0 + K(S - E)
(source, emphasis mine)
Though at one point the
K value was calculated for each player from the pre-event rating, it is now defined by one of two expressions depending on whether the tournament is "half-K" or "full-K:"
The value of K, which used to take on the values 32, 24 or 16, depending only on a player's pre-event rating, is now defined as...
(source: same page as above)
What does it mean if a tournament is half-K (besides that it changes the value of K)? Why would the tournament director choose to make an event half-K?
I also see that the USCF considered removing the half-K option, then did remove it, then considered using it for quick games in some way. However, none of those reports explain what being half-K actually does to a tournament.