Fractions of permutations. An application to Sudoku

We study how to simplify fractional factorial design generation by exploiting the a priori knowledge that can be derived from the orthogonality constraints that the fractional factorial design itself must satisfy. We work on Sudoku puzzles that can be considered as a special case of Latin squares in the class of gerechte designs. We prove that the generation of a Sudoku is equivalent to that of a fraction of a proper set of permutations. We analyse both the 4×4 and the 9×9 Sudoku types.     

The Relationship between Economics and Sociology: The Contribution of Economic Sociology,Setting out from the Problem of Embeddedness

This essay aims to analyse the most recent acquisitions in economic sociology, setting out from the problem of embeddedness. Firstly, the contribution offered by Mark Granovetter shall be illustrated, demonstrating how the interpretation proposed by this scholar is concentrated on a structural–relational perspective that tends to trace the explanation of economic phenomena to a theory of social networks. In order to enrich and integrate this approach, the contribution offered by the new-institutionalist perspective in contemporary economic sociology will be emphasised, which has focused on the social construction of economic institutions. This current has underlined, on the one hand, the cognitive dimension of embeddedness, related to the way in which the uniformities structured by mental processes limit economic reasoning, and, on the other, the cultural dimension of embeddedness, concerning the role of collectively shared representations in the formation of economic goals. It will be concluded by illustrating the acquisitions of some theoretical perspectives linked to the polanyian tradition that have developed a ‘plural’ conception of economy, founded on the emphasis of socio-regulative principles, such as those of exchange, redistribution and reciprocity, which, in becoming hybrid, give shape to variable and historically anchored economic worlds. The concept of embeddedness roots historically and transmits a vision of economic processes as inseparable from non-economic institutions.     

Semiparametric Modeling of the Spatial Distribution of Occupational Accident Risk in the Casual Labor Market, Piracicaba, Southeast Brazil

The objective of this study was to estimate the spatial distribution of work accident risk in the informal work market in the urban zone of an industrialized city in southeast Brazil and to examine concomitant effects of age, gender, and type of occupation after controlling for spatial risk variation. The basic methodology adopted was that of a population-based case-control study with particular interest focused on the spatial location of work. Cases were all casual workers in the city suffering work accidents during a one-year period; controls were selected from the source population of casual laborers by systematic random sampling of urban homes. The spatial distribution of work accidents was estimated via a semiparametric generalized additive model with a nonparametric bidimensional spline of the geographical coordinates of cases and controls as the nonlinear spatial component, and including age, gender, and occupation as linear predictive variables in the parametric component. We analyzed 1,918 cases and 2,245 controls between 1/11/2003 and 31/10/2004 in Piracicaba, Brazil. Areas of significantly high and low accident risk were identified in relation to mean risk in the study region (p < 0.01). Work accident risk for informal workers varied significantly in the study area. Significant age, gender, and occupational group effects on accident risk were identified after correcting for this spatial variation. A good understanding of high-risk groups and high-risk regions underpins the formulation of hypotheses concerning accident causality and the development of effective public accident prevention policies.     

Social Cost Pricing when Public Transport is an Option Value

A well-known principle of welfare economics states that an efficient allocation of resources can be achieved in a competitive economy when market prices are in line with social marginal costs. When applied to the transport sector, this implies that the price of the various transport modes should be made equal to the sum of marginal production and external costs, like congestion, accidents, pollution, and road maintenance. It is sometimes argued the internalization of external costs would bring about a change in demand patterns with a shift towards public transport and cleaner modes. But public transport is already favoured by discriminatory fiscal treatment. Whereas public services are normally (heavily) subsidized, private transport is taxed in several ways and, in some countries, quite substantially so. The application of the 'optimal pricing' principle, therefore, critically depends on how the subsidization of public services is interpreted. This paper addresses the issue of optimal pricing of urban transport, using different hypotheses concerning the treatment of public services. After reviewing some traditional arguments in favour of public transport subsidization, a new approach, based on uncertainty and option values, is discussed. The implications of this approach are investigated by means of an applied model, where optimal prices for urban transport services in the city of Bologna are computed under alternative assumptions.     

Measure of internalized sexual stigma for lesbians and gay men: a new scale

The goal of this study is to propose a new Measure of Internalized Sexual Stigma for Lesbians and Gay Men (MISS-LG) that assesses three dimensions of internalized homonegativity: identity, social discomfort, and sexuality. A convenience sample of 735 Italian lesbians and gay male participants was used to demonstrate the psychometric validity of the scale. Results of confirmatory factor analysis supported three identifiable factors reflecting theoretically based constructs of the MISS-LG. The correlations with other instruments demonstrate the convergent validity: lesbian and gay participants with high internalized sexual stigma describe lower levels of self-disclosure and wellbeing. Implications for research and practice are discussed.     

Tools for evaluating EU agricultural policies: An integrated approach

The aim of this paper is to propose a theoretical “multi-phase” strategy for analysing in dynamic terms the territorial impact of agricultural and environmental EU policy measures. This approach should also allow to evaluate the adjustment capability of farms as a function of the characteristics of different territories. The proposed methodology is illustrated by an example using data relative to the 41 provinces of Northern Italy. In the first step, a multivariate statistical analysis (MSA) consisting in Principal Component Analysis and Cluster Analysis leads to the identification of homogeneous clusters of territorial units. The territorial mapping is conditional to a predetermined set of indicators that takes into account different aspects of agricultural development. In a second step, Positive Mathematical Programming (PMP) allows to introduce the impact of agricultural policies (compensatory payments, price changes, etc.) returning different scenarios of land use and agricultural profitability. According to the outputs of the PMP, the third step consists in a new MSA for detecting any changes in the territorial mapping. Convergence analysis can then synthesise the impact of the different policy options.     

The development of global IT infrastructure

A research model of the impact of a multinational corporations’ (MNC) global strategic orientation on global IT infrastructure was developed using global integration, or the degree to which a global strategy is actually implemented, as a mediator. A “matched pair” survey of 94 MNCs was conducted (two respondents per firm) in order to guard against common source bias. The results showed that the firms that pursue a globally oriented strategy actually enacted these strategies as indicated by a wide-variety of resource flows across national units. The role of the level of global integration as a mediator between global strategic orientation and global IT capabilities was empirically demonstrated. This confirms that a global strategy is not sufficient to ensure that an enabling IT infrastructure will be developed; rather it is the actual level of integration and interdependence that is achieved as a result of the strategy that drives IT infrastructure. The primary areas in which global integration was found to be closely linked to the global IT infrastructure were human resources, which significantly influenced the reach, range, support services and planning of the global IT infrastructure, and information resources which significantly influenced the planning dimension of the infrastructure. These results strongly suggest that the transfer of people among national units creates an information needs “pull” which leads to the development of better IT infrastructure and that the “push” of standardized information also contributes positively.     

The effects of board size and ‘busy’ directors on the market value of Italian companies

This paper presents evidence that corporate governance quality measured by (1) the board size and (2) the fraction of directors that serve on more corporate boards, influences the market value of firms. The analysis is based in Italy, a country that is characterized by family and concentrated ownership, low legal protection of investors and pyramidal firm structures. Our empirical results suggest that the level of ‘busy-ness’ of corporate directors as a measure of board effectiveness has a significant influence on firm’s market performance. By contrast, we find limited evidence that board size has a substantial impact on the market valuation, except in small and medium enterprises and in some specific industry sectors.

Fractional Factorial Designs for Model-Based Evaluation of Customer Preferences

In this article, we explore the connection between Conjoint Analysis (CA) and a recent theory for minimum size orthogonal fractional factorial design generation (Fontana, 2013 Fontana , R. ( 2013 ). Algebraic generation of minimum size orthogonal fractional factorial designs: an approach based on integer linear programming . Computat. Statist. 28 : 241 – 253 .[Crossref], [Web of Science ®] , [Google Scholar]).

We show how searching for a minimum size OFFD that satisfies a set of constraints, expressed in terms of orthogonality between simple and interaction effects, is equivalent to solving an integer linear programming problem. It is worth noting that the methodology puts no restriction either on the number of levels of each factor or on the orthogonality constraints and so it can be applied to a very wide range of designs, including mixed orthogonal arrays. An algorithm, that has been implemented in SAS/IML, is briefly described.

The use of this algorithm during the design stage of a generic CA is shown in two applications.     

MARKET POWER AND INFORMATION REVELATION IN DYNAMIC TRADING

We study a strategic model of dynamic trading where agents are asymmetrically informed over common value sources of uncertainty. There is a continuum of buyers and a finite number n of sellers. All buyers are uninformed, while at least one seller is privately informed about the true state of the world. When n = 1, full information revelation never occurs in equilibrium and the only information transmission happens in the first period. With n > 1 the outcome depends both on the structure of the sellers' information and, even more importantly, on the intensity of competition allowed by the existing trading rules. When there is intense competition (absence of clienteles), information is fully and immediately revealed to the buyers in every equilibrium for n large enough, regardless of the number of informed sellers. On the other hand, for trading arrangements characterized by less intense forms of competition (presence of clienteles), for any n we always have equilibria where information is never fully revealed. Moreover, in that case, when only one seller is informed, for many parameter configurations there are no equilibria with full information revelation, even for large n. (JEL: C72, C78, D82, D83)