本研究以廣州的新車市場為例，使用假設性獨佔檢定同時分析產品和地理市場的界定。市場占有率往往是執法當局評斷合併案件是否對現有市場競爭狀態造成影響的標準或門檻，因此市場的界定在審查初期扮演極其重要的角色。市場界定涵蓋產品與地理市場兩個基本面向，原則上兩個面向應同時在界定時被考量，但過往文獻在實證操作上於分析消費者在不同區域間對於同產品的轉換購買行為前，會先行處理產品間的替代性購買行為來進行產品市場的界定，但在現實中，消費者在替代性產品的選擇和同產品於區域間的轉換消費情形會同時發生，分開討論可能會產生兩者界定結果不一致的問題。因此本研究以廣州市2009至2013年的新車銷售市場為例進行產品與地理市場界定的同時性分析，第一階段我們採用考量消費者異質性和價格內生性的BLP模型進行新車市場的需求估計，第二階段則採用假設性獨佔檢定界定產品和地理市場。實證結果顯示，在產品與地理市場的界定上確實存有不一致的結果，為了有效衡量相關市場內產品的競爭情況進而界定市場，除了可先依照過往文獻常用的做法，將替代性高的產品列入考量外，也可在執行假設性獨佔檢定的程序中優先考慮擴展地理區域來進行界定，因此本研究為未來的相關研究提供一個可參考的做法。

This study takes Guangzhou's new vehicle market as an example and uses the hypothetical monopoly test (HMT) to simultaneously analyze the definition of products and geographic markets. The market share is often the standard or threshold for competition authorities to judge whether a merger case will affect the competitiveness of the market. Therefore, the market definition plays a significant role in the initial stage of the investigation. The market definition covers the two fundamental aspects of product and geographic market. In principle, both product and geographic aspects should be considered at the same time when defining the markets. However, previous studies in the empirical operation will analyze the switching behavior of consumers in different regions for the same product, after dealing with the substitute purchasing behavior between differential products to define the product market. In the real world, the choice of purchasing alternatives and the switch to distance suppliers of the same goods will happen at the same time. Discussing the definition of product and geographic markets separately may lead to an inconsistent result. Therefore, this study uses the new vehicle market in Guangzhou from 2009 to 2013 to analyze the product and geographic markets simultaneously. In the first stage, we adopt the BLP model, which considers consumer heterogeneity and endogeneity of price, to estimate the demand of the automobile market. In the second stage, the HMT is implemented to define the products and geographical markets. The empirical results show that there are indeed inconsistencies in the results of the products and geographic markets definition. To effectively measure the competition of products in the relevant markets and then define the market, apart from including the closest alternative products that commonly executed in the previous literature, the expansion of the region with the original product may be prioritized to examine in the procedure of the HMT. Therefore, this research provides a referable way for the related studies in the future.

Amelio A. and D. Donath, (2009) “Market Definition in Recent EC Merger Investigations: The Role of Empirical Analysis,” Concurrences Review, 3, 1-6.

Besenahan, T. (1987), “Competition and Collusion in the American Automobile Oligopoly: The 1995 Price War,” Journal of Industrial Economics, 35, 457-482.

Berry, S. T. (1994), “Estimating Discrete-Choice Models of Product Differentiation,” The RAND Journal of Economics, 25, 242-262.

Berry, S., J. Levinsohn, and A. Pakes (1995), “Automobile Prices in Market Equilibrium,” Econometrica, 63, 841-890.

Coate, M. B. and J. H. Fischer (2008), “A Practical Guide to the Hypothetical Monopolist Test for Market Definition,” Journal of Competition Law and Economics, 4, 1031-1063.

Chen, C. W. and W. M. Hu (2015), “Using the Hypothetical Monopolist Test to Define Relevant Markets in China’s Automobile Industry,” Fair Trade Quarterly, 23, 135-166.

Christensen, L.R., D.W. Jorgenson, and L.J. Lau (1975), “Transcendental Logarithmic Utility Functions,” American Economic Review, 65, 367–383.

Coate, M. B. and A. E. Rodriguez (2002), “Pitfalls in Merger Analysis: The Dirty Dozen,” New Mexico Law Review, 30, 227-252.

Davis, P. and E. Grace (2009), Quantitative Techniques for Competition and Antitrust Analysis, Princeton, N.J.: Princeton University Press.

Deaton, A. and J. Muellbauer (1980), “An Almost Ideal Demand System,” American Economic Review, 70, 312-326.

Fair Trade of Commission (2015), “Fair Trade Act of 2015”, retrieved on June 11, 2018. https://www.ftc.gov.tw/internet/english/doc/docDetail.aspx?uid=655&docid=13970.

Friberg R. and A. Romahn (2015), “Divestiture Requirements as a Tool for Competition Policy: A Case from the Swedish Beer Market,” International Journal of Industrial Organization, 42, 1-18.

Gorman, W.M. (1959), “Separable Utility and Aggregation,” Econometrica, 27, 469-481.

Ivaldi, M. and S. Lorincz (2011), “Implementing Relevant Market Tests in Antitrust Policy: Application to Computer Servers,” Review of Law & Economics, 7, 29-71.

Mcfadden, D. (1973), “Conditional Logit Analysis of Qualitative Choice Behavior,” Frontiers in Econometrics, 1st ed., Academic Press, 105-142.

Mcfadden, D. (1978), “Modeling the Choice of Residential Location,” in A. Karlgvist et al., eds., Spatial Interaction Theory and Planning Models, Amsterdam: North-Holland.

Moresi, S. X., S. C. Salop, and J. R. Woodbury (2008), “Implementing the Hypothetical Monopolist SSNIP Test with Multi-Product Firms,” Antitrust Source, 7. Available at http://www.abanet.org/antitrust/at-source/08/02/Feb08-Moresi.pdf.

Nevo, A. (2000), “A Practitioners’ Guide to Estimation of Random-Coefficients Logit Models of Demand,” Journal of Economics Management Strategy, 9, 513-548.

Nevo, A. (2001), “Measuring Market Power in the Ready-to-Eat Cereal Industry,” Econometrica, 69, 307–342.

Nakamura, E., D. Zerom (2010), “Accounting for Incomplete Pass-Through,” Review of Economic Studies, 77, 1192-1230.

Stone, J. (1954), “Linear Expenditure Systems and Demand Analysis: An Application to the Pattern of British Demand,” Economic Journal, 64, 511-527.

Scheffman, D., M. Coate, and L. Silvia (2003), “Twenty Years of Merger Guidelines Enforcement at the FTC: An Economic Perspective,” Antitrust Law Journal, 71, 277-318.

Theil, H. (1965), “The Information Approach to Demand Analysis,” Econometrica, 6, 375-380.

U.S. Department of Justice (2010), “Merger Guidelines,” Antitrust Trade Regulation Report, 2010, No. 1069, retrieved on July 27, 2018. https://www.justice.gov/atr/horizontal-merger-guidelines-08192010.

Villas-Boas, S. B. (2007), “Vertical Relationships between Manufacturers and Retailers: Inference with Limited Data,” Review of Economic Studies, 74 (2), 625–652.

Vincent, D. W. (2015), “The Berry-Levinsohn-Pakes Estimator of the Random-Coefficients Logit Demand Model,” The Stata Journal, 15, 854-880.

Xiao, J., X. Zhou, and W. M. Hu (2017), “Welfare Analysis of the Vehicle Quota System in China,” International Economics Review, 58, 617-650.