 Glickman's principal contribution to measurement is "ratings reliability", called RD, for "ratings deviation".Both Glicko and Glicko-2 rating systems are under public domain and found implemented on game servers online (like Pokémon Showdown, Lichess, Free Internet Chess Server, Chess.com, Online Go Server (OGS), , Team Fortress 2, Dota Underlords, Guild Wars 2, Splatoon 2, and Dominion Online), and competitive programming competitions.The formulas used for the systems can be found on the Glicko website.