Weyl and Fabinger (2013) analyze the social incidence of competition and the output and welfare effects of third-degree price discrimination by considering the hypothetical entrance of exogenous quantity into a market. The formulas they use for this purpose, however, are correct only for marginal changes in exogenous quantity starting at zero or if demand functions are linear. We show how using the correct formulas changes Weyl and Fabinger’s analyses and leads to new results on the social incidence of competition and on the output and welfare effects of third-degree price discrimination in monopoly and oligopoly markets.

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评论：传递作为经济工具——论外生竞争、社会发生率和价格歧视

Weyl 和 Fabinger (2013) 通过考虑外生数量进入市场的假设，分析了竞争的社会发生率以及三级价格歧视的产出和福利效应。然而，他们为此目的使用的公式仅适用于从零开始的外生数量的边际变化，或者如果需求函数是线性的。我们展示了使用正确的公式如何改变 Weyl 和 Fabinger 的分析，并导致关于竞争的社会发生率以及垄断和寡头垄断市场中三级价格歧视的产出和福利影响的新结果。