Balanced experimental designs, in which the number of treatment and control units are the same, do not maximize power subject to a cost constraint when treat-ment units are more expensive than control ones. Despite this, such balanced designs are the norm in economics. This paper describes...

Balanced experimental designs, in which the number of treatment and control units are the same, do not maximize power subject to a cost constraint when treat-ment units are more expensive than control ones. Despite this, such balanced designs are the norm in economics. This paper describes...