Correlation,causality, and all that jazz: The inherent shortcomings of price tests for antitrust market delineation

A substantial economics literature has developed in which price data have been relied upon to delineate antitrust markets by empirically implementing definitions offered by classical economists. The forces driving these price tests are not the same as those that give rise to market power, and therefore these price tests are likely to reach erroneous conclusions if used to delineate antitrust relevant markets. The price tests should be used with great caution, if at all.     

Price and market policy for agriculture

The focus of this policy assessment is on the recent history of regulatory measures in market-oriented economies where the dominating triad of problems is stablisation, farm income support and market surplusses. Alternative forms of intervention are reviewed with respect to their impact on domestic supply and demand, international trade, farm income and labour, and finally how they cope with the process of change in agriculture. The author concludes that stabilisation policies in agriculture are not suitable for perishables where they can easily become a burden for consumers and governments alike.     

Market definition,market power

Market definition and market power are central features of competition law and practice but pose serious challenges. On one hand, market definition suffers decisive logical infirmities that render it infeasible, unnecessary, and counterproductive, and the practice of stating market power requirements as market share threshold tests is incoherent as a matter of empirics and policy. On the other hand, market power is often probative of the desirability of liability, yet the typically assumed functional relationship is unexplored and often implausible. These latter deficiencies are addressed through a ground-up analysis of the channels by which market power can be relevant. It is important to explicitly and simultaneously consider both anticompetitive and procompetitive explanations for challenged practices and to attend to the magnitudes of the social consequences of correct and mistaken imposition of liability in order to identify the various ways and senses in which market power bears on optimal decision-making.     

Strategic market analysis and definition: An integrated approach

Two distinct approaches to market analysis and definition have evolved. Those approaches which adopt a top-down persepective, tend to specify markets in terms of competitive capabilities and resource transferability. The alternative bottom-up perspective emphasizes customer requirements or usage patterns when defining markets. An integrated approach begins with a common model of the principal dimensions of a market. The second element is the recognition that different market definitions are needed for different strategic purposes. Next, the strategic planning framework which links business units and product-market units should be compatible with these purposes and reflect a strategically relevant balance of cost and demand factors. A procedure for forming business units from groups of product-markets is shown to be effective for achieving this balance.     

Input market definition under department of Justice Merger Guidelines

This paper applies the Justice Department's Merger Guidelines to define a relevant antitrust market for an input. An expression for the elasticity of the residual demand facing a monopoly supplier of a factor of production is derived. It is shown that proper input market definition depends on the elasticity of residual demand confronting the downstream input users, on the supply elasticity in the downstream market (which, in turn, depends on the rate of capital depreciation there), on the cost of the input as a percentage of downstream sales, and on the extent to which the monopolist is integrated downstream.     

Price dispersion in a market with advance-purchases

This paper examines price discrimination in a market where consumers learn their preferences over time. The products are perfect substitutesex ante, but there is horizontal differentiationex post. Air travel provides one example of such a market. In equilibrium, there is more price discrimination under duopoly than under monopoly, which is consistent with recent empirical evidence from the U.S. airline industry.I am grateful to Tom Holmes for many discussions on related topics.     

Vertical relations,pass-through,and market definition: Evidence from grocery retailing

We examine how different pass-through rates from input prices to retail prices and different vertical contracts affect upstream market definition. Simple theoretical considerations suggest that vertical restraints induce higher pass-through rates and thus lead to a larger upstream market definition when compared to linear wholesale pricing, given that contracts with linear pricing are associated with lower pass-through rates under imperfect competition. Data from grocery retailing is used to quantify the empirical implications of our theoretical assertion. We find that resale price maintenance leads to larger upstream market definitions than linear pricing. We therefore advise competition authorities to carefully model vertical market structures, whenever they expect incomplete pass-through to be important.     

Wholesale market definition in telecommunications: The issue of wholesale broadband access

The scope of a wholesale market may, in addition to demand- and supply-side substitution at the wholesale level, also be determined by substitution patterns at the retail level. Considering wholesale broadband access markets, it is argued that each of these forces can be strong enough to render a 5–10% price increase by a hypothetical monopolist at the wholesale level unprofitable and thus may lead to a wider wholesale market definition including, for example, cable networks in addition to DSL. Based on the theory of derived demand elasticities the paper discusses under which circumstances this could be the case. The position of the European Commission and the practice of national regulatory authorities are then reviewed in light of these arguments.     

Price changes and trading volume relationship in the Hong Kong stock market

Studies on the relationship between price changes and trading volume can provide insight into the structure of the financial market. In this paper, we will study the above topic and concentrate on the stock market of Hong Kong. The correlation between price changes and trading volume as well as that between the magnitude of price changes and trading volume will be examined. We will also check the asymmetry of the price changes and volume relationship. Moreover, we will investigate the relationship between the variance of return and trading volume. Finally, the Granger causality test of price changes and volume will be performed.     

Alternatives to the U.S. Antitrust Agency approach to market definition

Shortcomings of the U.S. Antitrust Agency Guidelines method of market definition include failure to focus on competition, the need for cost data, and discontinuities. Two alternative approaches are presented which avoid these problems and the Guidelines' inclusion of substitutes on an all-or-nothing basis. One alternative focuses on the size of a change in capacity of a substitute that would be needed to have the same effects as a unit change in capacity of an initial item. The second proposed alternative offers a simple operational method of giving practical content to the “reasonable interchangeability” concept which is a prominent feature of U.S. Supreme Court decisions. The alternative approaches are evaluated in comparison to that of the Guidelines and some modified versions of the latter.     

The influence of secondary production on industry definition in the extended vertical market model

Secondary production is defined and its role in the estimation of an extended vertical market model b examined. Two impacts on the subject industry are identified, called primary product dominance and primary product focus. A simultaneous equations model consisting of a profit equation and two secondary production equations is estimated using data from the interindustry transactions accounts. The profit equation captures the impact on industry profit of secondary production and of extended market structure. The dominance equation captures the relationship between secondary production and industry profit and scale of production. The focus equation captures the relationship between secondary production and industry profit and excess capacity. The model is estimated for all industries, and the common specification is then applied to industries grouped by type.     

垂直市场结构、价格稳定性与国内石油税制选择

运用垂直市场结构方法研究不完全竞争的石油市场中不同税制对国内石油价格稳定性的差异化影响及其税制选择。研究发现,在不同的垂直市场结构组合下,从价税制和从量税制对国际石油市场冲击的价格传递弹性明显不同;税制选择主要依赖于各国石油业的竞争性及其石油需求弹性;在大多数情形下从价税制都是更优的税制选择。对中国的启示是,如需要考虑国内石油价格的稳定性,在中国很强的石油业垄断格局及特定的石油需求弹性情形下,从价税制可能是较好的税制选择。     

Agricultural factor markets in Sub-Saharan Africa: An updated view with formal tests for market failure

This paper uses the recently collected Living Standard Measurement Study–Integrated Surveys on Agriculture Initiative data sets from five countries in Sub-Saharan Africa to provide a comprehensive overview of factor market participation by agrarian households and to formally test for failures in rural markets. Under complete and competitive markets, households can solve their consumption and production problems separately, so that household factor endowments do not predict input demand. This paper implements a simple, theoretically grounded test of this separation hypothesis, which can be interpreted as a reduced form test of market failure. In all five study countries, the analysis finds strong evidence of factor market failure. Moreover, those failures appear general and structural, not specific to subpopulations defined by gender, geography, human capital, or land quality. However, we show that rural markets are not generally missing in an absolute sense, suggesting that market existence is less of a problem than market function.     

Applying “Merger Guidelines” market definition to (de)regulatory policy: Pros and cons

Since initially presented in the 1982 Department of Justice Horizontal Merger Guidelines, market definition has been adopted nearly worldwide as a framework to see if a merger would substantially lessen competition. This framework is useful for addressing the similarly counterfactual question of whether forbearance from regulation would lead to an increase in prices. In this context, however, the usefulness of a merger-based market definition is limited. Because the alternative to forbearance is regulation, and since some regulated rates may be below competitive levels, finding that deregulation would lead to market power as defined for mergers need not justify continued regulation. Forbearance in telecommunications highlights market definition questions regarding gross vs. marginal substitutes, dynamic efficiencies, and service bundling. It also reveals ambiguities in the meaning of “geographic market.” Market definition also has limited applicability if regulation exists not to prevent high prices but the abuse of dominance through predatory pricing.     

Do Asian stock market prices follow martingales? Evidence from spectral shape tests

This paper examines the martingale hypothesis for five Asian stock markets using the spectral shape tests of Durlauf (1991). Unlike the variance ratio test employed in previous studies (eg, Panet al, 1991), the spectral shape tests are consistent againstall stationary alternatives to the martingale null.The spectral shape tests were applied to daily and weekly returns on the stock indices of Thailand, Hong Kong, Korea, Malaysia and Taiwan over a period of 17 years. The results show that the martingale null is rejected for most markets. There is some evidence that the rejections may be due to low frequency or long memory influences.The authors are lecturers, Department of Finance and Banking, National University of Singapore. This paper was presented at the Third International Conference on Asian-Pacific Financial Markets, September 9–11, 1993 in Singapore. We have benefited greatly from the comments of Y K Tse and other conference participants.     

Evaluating traditional share—Price and residual demand measures of market power in the catsup industry

In this paper we specify a price determination model which can test both the traditional positive interbrand price—share hypothesis and the negative intrabrand relationship predicted by residual demand analysis. We evaluate this relationship empirically using three-dimensional panel data from the catsup industry. We find support for both hypothesized relationships, and conclude that market power exists in this industry. Further, we conclude that the results depend critically on the characteristics of the data set to be analyzed.     

Price convergence in contestable market structures: The impact of time and price-caps on intercity telecommunications rates

In this study, we tested if long-distance rates among AT&T, MCI, and US Sprint between New York City and six major SMSAs during 1980–91 have converged. Empirical findings show that rates have converged over time, that rate ratios or differences increased under price cap, and that distance does not have any impact on rate convergence. The variables of TIME and price cap (CAP) have greater impacts on rate convergence for AT&T/US Sprint than AT&T/MCI. Regression results based on pooled cross-section and time-series data yield better results.     

A note on causality and the structure-performance controversy

Interindustry, cross-sectional studies of structure and performance assume, according to the market power doctrine, that structural variables are exogenous to performance, though this notion has been questioned at different times by a number of industrial organization economists. This study uses a time series approach to test the validity of this notion at the line of business level. Sims' causality tests were performed for three separate firms and the interrelationships over time between the firm's market share and rate of return were estimated (i.e., do changes in a firm's market share occur prior to changes in the firm's rate of return or do changes in the firm's rate of return occur prior to changes in a firm's market share). Two of the three firms examined failed to exhibit the unidirectional causality assumed by the conventional structure-performance paradigm. These results, even though derived from a limited number of undiversified firms, suggest that the issue of causality must be settled before the functional form of the model can be specified.