The average contributed method of calculation of MGR or rakeback is dependent on the contributions made by the player. Under this method a player has to be dealt with and he also has to make contribution to the pot in some way.
The formula is: MGR = amount raked in the pot / number of players who contributed to the pot.
For example if there are only 5 players who are dealt with and only 3 contribute to the pot and theamount raked is $3 then each contributed player will get = $1 that is $3/3.