We study a two-period model of a duopoly with goods differentiated by quality. The periods’ length corresponds to the goods’ useful lifespan, and consumers are heterogeneous in their valuation of quality. In the second period, the regulator fixes a minimum quality standard based either on the quality supplied by the high-quality firm in the first period (strict regulation) or on the average quality supplied in the first period (average regulation). Assuming a covered market, we show that such an approach leads to decreasing qualities in the first period, and increasing qualities in the second one. In both periods, net utility aggregated over consumers is increasing and profits aggregated over firms are decreasing. Taken together, average regulation always leads to an increase in the present value of welfare, whereas strict regulation can cause a decline. If the discount factor exceeds a certain threshold, a policy based on average regulation is even superior to implementing the optimal minimum quality standard already in the first period.

我们研究了一个双头垄断的两期模型，其中商品按质量进行区分。期间的长度对应于商品的使用寿命，消费者对质量的评价是异质的。在第二阶段，监管机构根据第一阶段优质公司提供的质量（严格监管）或第一阶段提供的平均质量（平均监管）确定最低质量标准。假设一个覆盖市场，我们表明这种方法会导致第一阶段的质量下降，而第二阶段的质量提高。在这两个时期，消费者的净效用都在增加，而企业的利润却在减少。总而言之，平均管制总是导致福利现值的增加，而严格的监管可能会导致下降。如果贴现因子超过某个阈值，基于平均监管的政策甚至优于已经在第一期实施的最优最低质量标准。