Social capital as social networks: A new framework for measurement and an empirical analysis of its determinants and consequences

The contribution of this paper to the social capital literature is threefold. First, we set up a new framework for measurement, allowing us to build indicators for five different dimensions of the concept. Second, we provide a single, synthetic, measure capturing that particular configuration of social capital which the literature generally associates with positive economic outcomes. Third, we carry out an empirical assessment of the relationships between the different types of social capital identified by our analysis and a range of socio-economic phenomena.     

INVESTMENT AND TIME TO PLAN AND BUILD: A COMPARISON OF STRUCTURES VS. EQUIPMENT IN A PANEL OF ITALIAN FIRMS

“Time‐to‐build” models of investment expenditures play an important role in many traditional and modern theories of the business cycle, especially for explaining the dynamic propagation of shocks. We estimate the structural parameters of a time‐to‐build model using annual firm‐level investment data on equipment and structures. For expenditures on equipment, we find no evidence of time‐to‐build effects beyond one year. For expenditures on structures, by contrast, there is clear evidence of such effects in the range of two to three years. The contrast between equipment and structures is intuitively reasonable and consistent with previous results. The estimates for structures also indicate that initial‐period expenditures are low and increase as projects near completion. These results provide empirical support for including “time‐to‐plan” effects for investment in structures. More generally, these results suggest a potential source of specification error for Q models of investment and production‐based asset pricing models that ignore the time required to plan, build, and install new capital. (JEL: D24, G31, C33, C34)     

Outlier detection in contingency tables based on minimal patterns

A new technique for the detection of outliers in contingency tables is introduced, where outliers are unusual cell counts with respect to classical loglinear Poisson models. Subsets of cell counts called minimal patterns are defined, corresponding to non-singular design matrices and leading to potentially uncontaminated maximum-likelihood estimates of the model parameters and thereby the expected cell counts. A criterion to easily produce minimal patterns in the two-way case under independence is derived, based on the analysis of the positions of the chosen cells. A simulation study and a couple of real-data examples are presented to illustrate the performance of the newly developed outlier identification algorithm, and to compare it with other existing methods.     

On implementation of the Gibbs sampler for estimating the accuracy of multiple diagnostic tests

Implementation of the Gibbs sampler for estimating the accuracy of multiple binary diagnostic tests in one population has been investigated. This method, proposed by Joseph, Gyorkos and Coupal, makes use of a Bayesian approach and is used in the absence of a gold standard to estimate the prevalence, the sensitivity and specificity of medical diagnostic tests. The expressions that allow this method to be implemented for an arbitrary number of tests are given. By using the convergence diagnostics procedure of Raftery and Lewis, the relation between the number of iterations of Gibbs sampling and the precision of the estimated quantiles of the posterior distributions is derived. An example concerning a data set of gastro-esophageal reflux disease patients collected to evaluate the accuracy of the water siphon test compared with 24 h pH-monitoring, endoscopy and histology tests is presented. The main message that emerges from our analysis is that implementation of the Gibbs sampler to estimate the parameters of multiple binary diagnostic tests can be critical and convergence diagnostic is advised for this method. The factors which affect the convergence of the chains to the posterior distributions and those that influence the precision of their quantiles are analyzed.     

Illegal Immigrants and the Informal Economy in Italy

ABSTRACT: The present work is divided into three parts. In the first part the (limited) empirical data relevant to the phenomenon in question is presented, that is, the growing illegality of Italian immigration and the illegal work that immigrants are destined to take up. Obviously the illegality of their presence and the íllicitness of the work are, by definition, phenomena which are difficult to quantify. Some estimates, albeit limited to certain regions, are nevertheless available and the picture that emerges is coherent with the present hypothesis. The hypothesis is then explained at a theoretical level, in the second part, where a simple model of general equilibrium is presented, referring to a two-sector economy with a single good. The model has the sole aim of illustrating the plausible characteristics of an economy characterised by the phenomenon that this present paper attempts to clarify. In the third part, to give an example, a simulation is put forward, utilising, in the model, values not incoherent with estimates based on Italy as a whole.     

Robust estimation in long-memory processes under additive outliers

In this paper, we introduce an alternative semiparametric estimator of the fractional differencing parameter in ARFIMA models which is robust against additive outliers. The proposed estimator is a variant of the GPH estimator [Geweke, J., Porter-Hudak, S., 1983. The estimation and application of long memory time series model. Journal of Time Series Analysis 4, 221–238]. In particular, we use the robust sample autocorrelations of Ma, Y. and Genton, M. [2000. Highly robust estimation of the autocovariance function. Journal of Time Series Analysis 21, 663–684] to obtain an estimator for the spectral density of the process. Numerical results show that the estimator we propose for the differencing parameter is robust when the data contain additive outliers.     

Mixing and moments properties of a non-stationary copula-based Markov process

Abstract

We provide conditions under which a non-stationary copula-based Markov process is geometric β-mixing and geometric ρ-mixing. Our results generalize some results of Beare who considers the stationary case. As a particular case we introduce a stochastic process, that we call convolution-based Markov process, whose construction is obtained by using the C-convolution operator which allows the increments to be dependent. Within this subclass of processes we characterize a modified version of the standard random walk where copulas and marginal distributions involved are in the same elliptical family. We study mixing and moments properties to identify the differences compared to the standard case.     

Perceptions about Compliant Flooring from Senior Managers in Long-Term Care

This study explored barriers and facilitators to adoption of compliant flooring as a fall injury prevention strategy within long-term care from the perspective of 18 long-term care senior managers. In-depth interviews were recorded, transcribed, and analyzed using the Framework Method. The most important organizational facilitators to adoption were potential for injury prevention and long-term care staff's openness to change. The most important organizational barriers to adoption were negative effects to long-term care staff and financial considerations (i.e., cost and lack of funding). The most important general organizational considerations were uncertainties about clinical effectiveness, effects on long-term care staff, and flooring performance. Overall, compliant flooring was viewed positively for long-term care. The findings also suggest an opportunity for knowledge translation to inform long-term care senior managers about the existing evidence on compliant flooring.     

TOPICS AND GEOGRAPHICAL DIFFUSION OF KNOWLEDGE IN TOP ECONOMIC JOURNALS

We study the evolution of topics in economics and their geographical specialization by analyzing 13,233 papers from seven top journals between 1985 and 2012 and their forward citations. The share of U.S. publications declines from 75% to 64% with a corresponding increase of the European share from 12% to 24%. We use topic modeling and document the evolution of the discipline over 27 years. We estimate, with a quasi‐structural model, the citation lag distribution for 18 different topics and three large geographical areas. The modal citation lag is about 6.7 years in the entire sample and 4.8 years for citations from the top 100 journals. We quantify (1) the home bias effect in citations, (2) how it fades away over time, (3) the long lasting impact of U.S. publications vis‐à‐vis other geographical areas, and (4) the higher speed of diffusion and faster obsolescence in the United States. (JEL A14, I23, O33, A11)     

Objective and Subjective Rationality in a Multiple Prior Model

A decision maker (DM) is characterized by two binary relations. The first reflects choices that are rational in an “objective” sense: the DM can convince others that she is right in making them. The second relation models choices that are rational in a “subjective” sense: the DM cannot be convinced that she is wrong in making them. In the context of decision under uncertainty, we propose axioms that the two notions of rationality might satisfy. These axioms allow a joint representation by a single set of prior probabilities and a single utility index. It is “objectively rational” to choose f in the presence of g if and only if the expected utility of f is at least as high as that of g given each and every prior in the set. It is “subjectively rational” to choose f rather than g if and only if the minimal expected utility of f (with respect to all priors in the set) is at least as high as that of g. In other words, the objective and subjective rationality relations admit, respectively, a representation à la Bewley (2002) and à la Gilboa and Schmeidler (1989). Our results thus provide a bridge between these two classic models, as well as a novel foundation for the latter.