Carmen Trueba

Modeling the probabilistic distribution of the impact factor

The study of the informetric distributions, such as distributions of citations and impact factors is one of the most relevant topics in the current informetric research. Several laws for modeling impact factor based on ranks have been proposed, including Zipf, Lavalette and the two-exponent law proposed by Mansilla et al. (2007). In this paper, the underlying probabilistic quantile function corresponding to the Mansillas two-exponent law is obtained. This result is particularly relevant, since it allows us to know the underlying population, to learn about all its features and to use statistical inference procedures. Several probabilistic descriptive measures are obtained, including moments, Lorenz and Leimkuhler curves and Gini index. The distribution of the order statistics is derived. Least squares estimates are obtained. The different results are illustrated using the data of the impact factors in eight relevant scientific fields.

The Lamé Class of Lorenz Curves.

ABSTRACT In this paper, the class of Lamé Lorenz curves is studied. This family has the advantage of modeling inequality with a single parameter. The family has a double motivation: it can be obtained from an economic model and from simple transformations of classical Lorenz curves. The underlying cumulative distribution functions have a simple closed form, and correspond to the Singh–Maddala and Dagum distributions, which are well known in the economic literature. The Lorenz order is studied and several inequality and polarization measures are obtained, including Gini, Donaldson–Weymark–Kakwani, Pietra, and Wolfson indices. Some extensions of the Lamé family are obtained. Fitting and estimation methods under two different data configurations are proposed. Empirical applications with real data are given. Finally, some relationships with other curves are included.

Assessing Global Inequality in Well-being Using Generalized Entropy Measures☆

Abstract In this paper we study global inequality in well-being taking as a reference the Human Development Index. One of the main changes applied to this indicator was the substitution of the arithmetic mean for a geometric mean in the construction of the index, thus assuming different substitution grades between dimensions. In order to determine the impact of the aggregation formula in the distribution of the HDI, we propose the use of multidimensional generalized entropy measures, which allow us to study the evolution of well-being inequality based on different aggregation schemes. The results obtained suggest a reduction in global inequality in human development over the period 1980- 2011. However different inequality patterns are observed depending on the substitutability parameter, thus pointing out the crucial role played by the aggregation formula of composite indices of well-being in the evolution of global inequality.

The n-fold convolution of a finite mixture of densities

Abstract In this paper, the probability density function of the n-fold convolution of a finite mixture of densities is obtained. The new density is again a finite mixture of densities. In this way, the formula recently given by Ma [N.-Y. Ma, A comment on “On the distribution of Ma and King, Applied Mathematics and Computation” 218 (2011) 202–203] for a two-fold convolution is interpreted and extended and a correct expression for the formula provided by Nadarajah [S. Nadarajah, On the distribution of Ma and King, Applied Mathematics and Computation 189 (2007) 732–733] is given. Several relevant examples are provided, including the convolution for the generalized exponential-sum distribution.

Statistical polarization in greenhouse gas emissions: Theory and evidence

The current debate on climate change is over whether global warming can be limited in order to lessen its impacts. In this sense, evidence of a decrease in the statistical polarization in greenhouse gas (GHG) emissions could encourage countries to establish a stronger multilateral climate change agreement. Based on the interregional and intraregional components of the multivariate generalised entropy measures (Maasoumi, 1986), Gigliarano and Mosler (2009) proposed to study the statistical polarization concept from a multivariate view. In this paper, we apply this approach to study the evolution of such phenomenon in the global distribution of the main GHGs. The empirical analysis has been carried out for the time period 1990-2011, considering an endogenous grouping of countries (Aghevli and Mehran, 1981; Davies and Shorrocks, 1989). Most of the statistical polarization indices showed a slightly increasing pattern that was similar regardless of the number of groups considered. Finally, some policy implications are commented.

Evolution of global inequality in human well-being: a sensitivity analysis

In this paper, we study global inequality in well-being taking as a theoretical benchmark the Human Development Index (HDI), which comprises variables of income, health and education. We use a two-step methodology that involves the construction of a composite index in the first step on which inequality measures are computed. The use of these measures requires making choices on the standardisation of the variables and their weights, the rate of substitution between dimensions and the degree of inequality aversion in the society. We investigate the impact of these choices on the evolution of unweighted inequality over the period 1980-2011. We find the robust result that global inequality in human well-being decreased over the last 30 years.