An extreme point characterization of random strategy-proof social choice functions: The two alternative case

We show that every strategy-proof random social choice function is a convex combination of strategy-proof deterministic social choice functions in a two-alternative voting model. This completely characterizes all strategy-proof random social choice functions in this setting.     

Ownership structure and cost efficiency: A study of publicly owned passenger-bus transportation companies in India

This paper estimates the determinants of cost inefficiency of several publicly operated passenger-bus transportation companies in India in terms of their ownership structure as well as other firm-specific characteristics. A panel data on publicly operated passenger-bus transportation companies is used to estimate a translog cost system with inefficiency. Inefficiency is specified in such a way that both its mean and variance are firm- and time-specific. For the estimation of production technology and cost inefficiency we have used a multi-step estimation procedure instead of the single-step maximum likelihood (ML) method. In the first step we estimate the translog cost system with heteroskedastic cost function without using any distributional assumptions on the error terms. The second stage uses the ML method to estimate the parameters associated with inefficiency, conditional on the parameter estimates obtained from the first stage. Finally, the residual of the cost function is decomposed to obtain firm-and time-specific measures of cost inefficiency, with ownership type and other firm-specific characteristics as explanatory variables.Financial support of the Nevada Agricultural Experiment Station is gratefully acknowledged.     

Nash implementation through elementary mechanisms in economic environments

This paper identifies a class of mechanisms, called elementary mechanisms, which are (in a precisely defined sense) the “simplest” mechanisms that can implement efficient outcomes in economic environments. The class of social choice correspondences that can be implemented by elementary mechanisms is completely characterized in a variety of different economic contexts.     

Dictatorial domains

Summary. In this paper, we introduce the notion of a linked domain and prove that a non-manipulable social choice function defined on such a domain must be dictatorial. This result not only generalizes the Gibbard-Satterthwaite Theorem but also demonstrates that the equivalence between dictatorship and non-manipulability is far more robust than suggested by that theorem. We provide an application of this result in a particular model of voting. We also provide a necessary condition for a domain to be dictatorial and use it to characterize dictatorial domains in the cases where the number of alternatives is three. Received: July 12, 2000; revised version: March 21, 2002 RID="*" ID="*" The authors would like to thank two anonymous referees for their detailed comments. Correspondence to: A. Sen     

Tops-only domains

In this paper we consider the standard voting model with a finite set of alternatives A and n voters and address the following question: what are the characteristics of domains \({\mathcal D}\) that induce the property that every strategy-proof social choice function \({f: {\mathcal D}^n \rightarrow A}\) satisfying unanimity, has the tops-only property? We first impose a minimal richness condition which ensures that for every alternative a, there exists an admissible ordering where a is maximal. We identify conditions on \({\mathcal D}\) that are sufficient for strategy-proofness and unanimity to imply tops onlyness in the general case of n voters and in the special case, n = 2. We provide an algorithm for constructing tops-only domains from connected graphs with elements of A as nodes. We provide several applications of our results. Finally, we relax the minimal richness assumption and partially extend our results.     

Nash implementation with partially honest individuals

We investigate the problem of Nash implementation in the presence of “partially honest” individuals. A partially honest player is one who has a strict preference for revealing the true state over lying when truthtelling does not lead to a worse outcome than that which obtains when lying. We show that when there are at least three individuals, all social choice correspondences satisfying No Veto Power can be implemented. If all individuals are partially honest and if the domain is separable, then all social choice functions can be implemented in strictly dominant strategies by a mechanism which does not use “integer/modulo games”. We also provide necessary and sufficient conditions for implementation in the two-person case, and describe some implications of these characterization conditions.     

Subgame perfect implementation: A necessary and almost sufficient condition

We present a necessary and almost sufficient condition for subgame perfect implementation of social choice correspondences. In societies with at least three individuals, any social choice correspondence which satisfies no veto power and our necessary Condition α is subgame perfect implementable. Thus Condition α is analogous to monotonicity which, by Maskin's celebrated characterization, is necessary and, in a similar way, almost sufficient for Nash implementation.     

Measuring Price Responsiveness Under a Profit Maximization Framework

The distinguishing feature of the study is in using a globally flexible functional form that permits one to calculate different types of elasticities under both constant and variable output hypotheses. The Symmetric Generalized McFadden cost function alongwith the output supply condition form the basis of the econometric model. To measure inputsubstitutabilities, we used Alien-Uzawa, Morishima, and Shadow elasticities of substitution. Empirical results, based on 300 farm households from West Bengal, India, show that fertilizer is most price sensitive input. It is a gross substitute for manure and human labor but complement to bullock labor. Manure is a gross substitute for all the inputs whereas human labor is gross complement to bullock labor. Using the Morishima measure we find that the fertilizer and bullock labor are complements when the price of the latterchanges. Similar complementary relationship is found between bullock and human labor due to changes in the price of human labor. All other inputs are Morishima substitutes. The Shadow elasticity of substitution estimates indicate that all factors are substitutes. The estimate of returns to scale indicates the presence of diminishing returns to scale.

     

Government Interventions, Market Imperfections, and Technical Inefficiency in a Mixed Economy: A Case Study of Indian Agriculture

This paper uses an output-maximizing framework in the presence of expenditure constraint to measure output loss and input misallocation resulting from market distortions and technical inefficiency. A generalized indirect production function accommodating allocative distortions and technical inefficiency is used. Allocative distortions are captured in terms of effective (shadow) prices in which distortion parameters are both farm- and input-specific. The stochastic frontier approach is used to model technical inefficiency. Using farm-level data on 105 jute growers from West Bengal, India, we find that average output losses due to allocative distortions and technical inefficiency are 6.3% and 14%, respectively.