SELECT player, SUM(partial_avg) / 3 AS shapley_value FROM ( SELECT player, size, SUM(partial_value) AS partial_avg FROM ( SELECT player, (project_comb_cost.value - project_addone_cost.value) / divisor AS partial_value, project_addone_cost.size AS size FROM project_comb_cost INNER JOIN project_addone_cost ON (project_comb_cost.comb = project_addone_cost.comb2) ) AS stratum GROUP BY player, size ) AS stratum_avg GROUP BY player ORDER BY player;