Measuring Substitution Patterns and Firm Conduct in Differentiated Product Industries

在这个项目中，采购经理人提出了一套新的工具，用于检测和衡量市场力量在行业中的重要性。这个问题是许多经济问题的核心。它与一系列反垄断问题特别相关，从批准合并到发现价格操纵案件，以及帮助指导金融服务、能源和电信等市场的监管机构。在大多数情况下，衡量市场力量取决于两个关键因素：(1)确定产品之间的替代程度；(2)量化其对市场价格的影响。这项工作的主要贡献在于，它将提供一套新的实证技术来衡量产品之间的替代程度，并帮助更好地识别差异化产品行业中的企业定价行为。在第一点上，PI建立在产业组织领域的一篇重要文献的基础上，致力于识别差异化产品市场的替代模式。这项工作的主要贡献是证明了数据中存在变异的来源，该来源推动了标准需求模型中产品之间的可替换性程度的识别。他们利用这种变化来构造文献中常用的模型的参数和非参数估计量(例如，Berry等人。(1995年)，内沃(2001年))。这涉及从业者就现有方法提供的预测的稳健性提出的重要储备(例如，Angrist和Pischke(2010))。关于第二点，物价指数提出了一种新的方法来从经验上估计价格和需求因素之间的供应关系，而不会强加强有力的、往往未经检验的假设。早期识别企业行为的努力依赖于对比观察到的需求传递或成本冲击对价格和数量的影响，以及来自竞争或串通模型的相当一般的理论预测(布雷斯纳汉，)。这种经验策略可以限制同质好产业的市场力量程度，但不能轻易扩展到卖家提供差异化商品和服务的环境。相比之下，研究差异化产品行业的市场支配力程度的研究人员通常依赖更严格的竞争模型，这往往完全消除了对替代行为假设进行测试的可能性；例如完全竞争或串通。为了解决这个问题，采购经理人将布雷斯纳汉(1987)的战略推广到具有潜在丰富产品差异化的环境中，测试协调定价的存在，允许更大类别的可能供应关系来确定企业行为。这反过来又允许直接检查企业在制定价格时如何利用市场力量，而不是以程式化的博弈论模型的形式假定它。

In this project, the PIs propose a new set of tools useful to detect and measure the importance of market power in industries. This question is central to many economic problems. It is particularly relevant for a vast array of antitrust questions ranging from the approval of mergers to the detection of price fixing cases, as well as to help guide regulatory institutions in markets such as financial services, energy, and telecommunication. In most of these cases, measuring market power hinges on two key elements: (i) identification of the degree of substitution between products, and (ii) quantification of its impact on market prices. The key contribution of the proposed work to this literature is that it will provide a new set of empirical techniques to both measure degree of substitutability between products, and help better identify firms' pricing conduct in differentiated product industries.On the first point, the PIs build on an important literature in the field of Industrial Organization, devoted to the identification of substitution patterns in markets for differentiated products. The main contribution of this work is to show the existence of a source of variation in the data that drives the identification of the degree of substitutability between products in standard demand models. They exploit this variation to construct parametric and non-parametric estimators of models commonly used in the literature (e.g. Berry et al. (1995), Nevo (2001)). This addresses important reserves raised by practitioners regarding the robustness of the predictions offered by existing methods (e.g. Angrist and Pischke (2010)). On the second point, the PIs propose a novel approach to empirically estimate the supply relationship between prices and demand factors, without imposing strong and often untested assumptions. Early efforts to identify firms' conduct have relied on contrasting observed measures of pass-through of demand or cost shocks on prices and quantities, with fairly general theoretical predictions from models of competition or collusion (Bresnahan, 1989). This empirical strategy can bound the degree of market power in homogenous good industries, but cannot easily be extended to settings in which sellers supply differentiated goods and services. In contrast, researchers studying the extent of market power in differentiated product industries typically rely on more restrictive models of competition, which often eliminates entirely the possibility of testing for alternative conduct assumptions; such as perfect competition or collusion. To get around this problem the PIs generalize Bresnahan's (1987) strategy for testing for the presence of coordinated pricing to an environment with potentially rich product differentiation, allowing for a larger class of possible supply relations to determine firm conduct. This allows in turn to directly examine how firms exploit market power when setting prices, rather than assuming it in the form of stylized game theoretic models.