In the first part of the DOA the greatest gains from trade occur only if the premium good is traded. In the second part, the greatest gains from trade occur only if the standard good is traded. In the third part, the greatest gains from trade occur only if some of the standard and some of the premium goods are traded. Asymmetric information could be introduced by having the product quality revealed only after the buyer has purchased the product. Also, one could introduce a 'government' quality standard in which low quality products are prohibited from trading.
Students play the role of used-car buyers.
Car buyers make a price offer and then roll a pair of dice to determine which type of car they receive. In general, to get a plum one must roll a large number. Students calculate their earnings based on the difference between the value of the car and the amount offered for it. Play is for three to five periods. Using Economic Experiments in the Classroom .