Modelling the propagation of adult male muscle dysmorphia in Spain: economic,emotional and social drivers

Males aged over 40 do more gym practice to improve their body image as a way of reinforcing their personal self-esteem and sexual appeal. Cases when self-image becomes an obsession may result in a body dysmorphic disorder named ‘muscle dysmorphia’ (MD). The combination of psychological, environmental and biological drivers determines the appearance and development of this disorder. In this article, we developed a discrete population mathematical model to forecast the rate of prevalence of males who are noncompetitive bodybuilders at risk of suffering MD in Spain in forthcoming years. Economic, emotional, sociological and psychological motivations were taken into account to quantify the dynamic behaviour of Spanish noncompetitive bodybuilders. The impact of the unemployment is reflected in the construction of two coefficients, α_u and α₂₁, which explain subpopulation transits due to the economy. Sociological influences, such as human herding and social propagation, were also considered. Our results predict an increase in Spanish noncompetitive bodybuilders suffering MD from 1% in 2011 to around 11% in 2015. Our model can be applied to any other western country where data are available and to another study period when the hypotheses are applicable.     

Input substitutability and vertical integration

Input substitutability in final production is a well-known motive for noncompetitive input producers to integrate with their customers. In models that characterize the noncompetitive input industry as a pure monopoly, whether such integration would increase or decrease final production is ambiguous. The analysis here breaks the total output effect into factor substitution and market power components and discovers that the output ambiguity is sensitive to the specific model of noncompetitive equilibrium assumed. For the empirically most important cases of industrial organization, the sole effect of input substitutability on output is likely to be an unambiguous output increase.For their helpful comments, I am indebted to Stephen Karlson, Li Way Lee, W. G. Shepherd, Stephen Spurr, Hal Varian, and the referee. Any errors in the paper persist in spite of them.     

Nonparametric Methods for Evaluating Economic Efficiency and Imperfect Competition

This article unifies and extends ideas from nonparametric production analysis and DEA for testing organizational efficiency. We show how the admissible price set can be restricted to account for prior information on prices. These restrictions may relate prices to input and output quantities in order to test noncompetitive behavior of the evaluated decision making unit. While the resulting efficiency tests cannot always be cast into linear programming problems, we discuss various solution strategies for the tests. Thereby we consider the question when does local optimality of the result guarantee global optimality. We also show how the decision maker's preferences, for example ranking information, can be adopted into DEA models in a simple manner. Finally, the approach with price restrictions is illustrated with an application to test noncompetitive behavior of the pulp and paper industries in Finland.     

Effective risk aversion in thin risk‐sharing markets

We consider thin incomplete financial markets, where traders with heterogeneous preferences and risk exposures have motive to behave strategically regarding the demand schedules they submit, thereby impacting prices and allocations. We argue that traders relatively more exposed to the market portfolio tend to behave in a more risk tolerant manner. Noncompetitive equilibrium prices and allocations result as an outcome of a game among traders. General sufficient conditions for existence and uniqueness of such equilibrium are provided, with extensive analysis of two‐trader transactions. Even though strategic behavior causes inefficient social allocations, traders with sufficiently high risk tolerance and/or high initial exposure to tradable securities obtain more utility gain in the noncompetitive equilibrium, when compared to the competitive one.