An Empirical Test of the Free Rider and Market Power Hypotheses: A Comment
评论了Mueller和Geithman（1991）对Sealy床垫公司纵向约束的实证研究，指出他们忽略了1980年后Sealy利润上升的事实，导致其检验结果不具决定性。
Willard F. Mueller and Frederick E. Geithman (1991) test the competing free-rider (efficiency) and market-power explanations of certain vertical restraints once used by the Sealy mattress company and declared illegal after 1980. They estimate that eliminating the restraints increased sales and argue that this supports only the market-power explanation. However, Mueller and Geithman overlook the rise in Sealy's profits that occurred after 1980, a fact which renders their test inconclusive. Copyright 1994 by MIT Press.