Public Goods without punishment
Instructions
You belong to a randomly
formed group of five players. You are given 20 points each and must decide
simultaneously on how much to invest to the common pool. The total contribution
is multiplied by ½ and added to EACH players payoff  independently
of whether this player contributed or not.
Check:
Question: Suppose
that players 1, 2 and 3 give 10 points each and players 4 and 5 contribute
nothing. What is the common pool? How many points will each player have?
Answer: 1, 2, and
3 end up with 25 points, the others with 35 points.
Question: What if
only player 1 gives 10 points and the others nothing?
Answer: Player 1 ends
up with 15 points, the others with 25.
Evaluations
Number of players: 25 (5 games)
Mean investment: 4.0 ±4.9
Mean payoff: 26.1 ± 5.6
Note

Usually one or two players contributed zero.

In one game nobody contributed anything.
 For more information and experimental results on the public good game
we refer to the work of Ernst Fehr et al.
Written by Christoph Hauert