The initial K-value was 30, but was changed to 5 in January , then changed to 15 in July Chess Engines Grand Tournament.

He wanted to focus on the chess playing part rather than the graphics, and so asked Tim Mann how he could get Junior to communicate with Winboard. In general, a beginner is around , a mid-level player is around , and a professional, around

Elo thought of a player's true skill as the mean of that player's performance random variable. Although a player might perform significantly better or worse from one game to the next, Elo assumed that the mean value of the performances of any given player changes only slowly over time.