Behavioral Game Theory

How many subjects should there be in an economic experiment? One answer to that question would be to draw on power rules for statistical significance. In short, you need enough subjects to be able to reasonably reject the null hypothesis you are testing. This approach, though, has never really been standard in experimental economics. There are two basic reasons for this - practical and theoretical.  From a practical point of view the power rules may end up suggesting you need a lot of subjects. Suppose, for instance, you want to test cooperation within groups of 5 people. Then the unit of observation is the group. So, you need 5 subjects for 1 data point. Let's suppose that you determine you need 30 observations for sufficient power (which is a relatively low estimate). That is 30 x 5 = 150 subjects per treatment. If you want to compare 4 treatments that means 600 subjects. This is a lot of money (at least $10,000) and also a lot of subjects to recruit to a lab. In simple term