The Dynamics of Retail Oligopolies

Dynamic Models, Retail Indusry, Markov perfect equilibrium, Oligopoly

Patient Welfare and Patient Compliance: An Empirical Framework for Measuring the Benefits from Pharmaceutical Innovation

The main goal of this paper is to develop an empirical framework for evaluating the patient welfare benefits arising from pharmaceutical innovation. Extending previous studies of the welfare benefits from innovation (Trajtenberg, 1990; Hausman, 1996), this paper unpacks the separate choices made by physicians and patients in pharmaceutical decisionmaking and develops an estimable econometric model which reflects these choices. Our proposed estimator for patient welfare depends on (a) whether patients comply with the prescriptions they receive from physicians and (b) the motives of physicians in their prescription behavior. By focusing on compliance behavior, the proposed welfare measure reflects a specific economic choice made by patients. We review evidence that the rate of noncompliance ranges up to 70%, suggesting an important gulf between physician prescription behavior and realized patient welfare. Since physicians act as imperfect but interested agents for their patients, the welfare analysis based on compliance must account for the nonrandom selection of patients into drugs by their physicians. The key contribution of this paper resides in integrating the choices made by both physicians and patients into a unified theoretical framework and suggesting how the parameters of such a model can be estimated from data.

Vertical product differentiation and competition in the supermarket industry

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Economics, 2000."February, 2000."Includes bibliographical references (leaves 130-137).This thesis examines the mechanisms by which retail markets converge to a concentrated structure where competition is dominated by only a few large firms. Using a model of competition based on the vertical product differentiation (VPD) enciogenous sunk cost framework proposed by Sutton (1991), several empirical implications are identified and evaluated using a detailed dataset of store level observations from the supermarket industry. Chapter 2 provides a formal test of the hypothesis that the high levels of concentration observed in the supermarket industry are the result of competitive investment in endogenous sunk costs. Using the bounds regression methodology developed in Sutton (1991), I document the existence of a large, positive lower bound to concentration that remains bounded above zero regardless of market size. This exercise is supplemented by a detailed case history of the industry that provides additional evidence that competition is focused on sunk outlays. In chapter 3, I expand the analysis by focusing on the local structure of competition. The principal contributions of the empirical work presented in this chapter involve identifying the high quality set of supermarket firms, demonstrating that they exist only in bounded numbers (do not increase proportionately with the size of the market), and identifying features of the observed market structure which are inconsistent with alternative explanations, namely by highlighting the distinctive nature of strategic complementarity. As such, I demonstrate that the VPD framework accords well with the combination of features observed in the supermarket industry, providing an accurate representation of the mechanisms sustaining its concentrated structure, which appear to be both competitive and stable. Three formal models of retail competition are presented in chapter 4, along with testable implications regarding the strategic interactions of rival firms.by Paul Bryan Ellickson.Ph.D

Pricing in inflationary times: The penny drops

How does the frequency and magnitude of micro-price rises and falls relate to macroeconomic crisis, as well as moderation? Weekly micropricing behaviour in British groceries was investigated across three leading retailers over the moderation period 2004–7 and the crisis period 2008–10. We find significant price flexibility sharply distinguished from behaviour observed in most previous works. Downward price flexibility increased markedly in 2008. Overall basket prices rise, but significantly more individual prices fall than rise in the latter period. Tests of obfuscation in price setting suggested that large numbers of small price falls were used to disguise the basket price rises

The logic of costly punishment reversed: expropriation of free-riders and outsiders

Current literature views the punishment of free-riders as an under-supplied public good, carried out by individuals at a cost to themselves. It need not be so: often, free-riders’ property can be forcibly appropriated by a coordinated group. This power makes punishment profitable, but it can also be abused. It is easier to contain abuses, and focus group punishment on free-riders, in societies where coordinated expropriation is harder. Our theory explains why public goods are undersupplied in heterogenous communities: because groups target minorities instead of free-riders. In our laboratory experiment, outcomes were more efficient when coordination was more difficult, while outgroup members were targeted more than ingroup members, and reacted differently to punishment