On Kendall's Autocorrelations

This brief article extends the theory of sample Kendall's autocorrelations by providing their exact variances at lags higher than one under the null hypothesis of randomness, by introducing and investigating their weighted modifications, and by numerical demonstration of these results and their usefulness.     

Marshall–Olkin q-Weibull distribution and max–min processes

In this paper, we introduce a new probability model known as Marshall–Olkin q-Weibull distribution. Various properties of the distribution and hazard rate functions are considered. The distribution is applied to model a biostatistical data. The corresponding time series models are developed to illustrate its application in times series modeling. We also develop different types of autoregressive processes with minification structure and max–min structure which can be applied to a rich variety of contexts in real life. Sample path properties are examined and generalization to higher orders are also made. The model is applied to a time series data on daily discharge of Neyyar river in Kerala, India.     

Using government manifestos to analyse the political salience and shape of anti-corruption policies in the Czech Republic and Slovakia

In an innovative use of government manifestos, this paper examines the salience and shape of anti-corruption policies in Slovakia and the Czech Republic during the period 1990–2013. Both the intensity and shape of anti-corruption efforts appear to be related less to the actual extent of corruption or external influences and more to the growing domestic electoral pressure expressed through the higher ranking of corruption on the list of public problems and to an ideological bent of governments. We also use cultural theory to examine the philosophy of anti-corruption measures. We find that the hierarchical approach clearly dominates, but there is also extensive evidence of an egalitarian approach. There are only a small number of individualist measures and there is nearly no evidence of fatalist measures. We found that the political right in both the Czech Republic and Slovakia is associated not just with an individualist and market-based approach to anti-corruption, but even more with emphasis on anti-corruption itself and empowerment, civil society and public accountability as a means of fighting corruption.     

On Exact Computation of Some Statistics Based on Projection Pursuit in a General Regression Context

It is shown in detail how recent advances in multiple-output and projectional quantile regression open the door to exact computation of many inferential statistics based on projection pursuit. This is also illustrated on a few examples including new regression generalizations of multivariate skewness, kurtosis, and projection depth.     

Approximation hardness of edge dominating set problems

We provide the first interesting explicit lower bounds on efficient approximability for two closely related optimization problems in graphs, MINIMUM EDGE DOMINATING SET and MINIMUM MAXIMAL MATCHING. We show that it is NP-hard to approximate the solution of both problems to within any constant factor smaller than . The result extends with negligible loss to bounded degree graphs and to everywhere dense graphs. An extended abstract of this paper was accepted at the 14th Annual International Symposium on Algorithms and Computation, ISAAC 2003.     

The Importance of Variables in Composite Indices: A Contribution to the Methodology and Application to Development Indices

The paper examines the issue of weights and importance in composite indices of development. Building a composite index involves several steps, one of them being the weighting of variables. The nominal weight assigned to a variable often differs from the degree to which the variable affects the scores of the overall index. The newly suggested notion of importance is based on the idea that an important indicator, if omitted from the index, causes large changes in countries’ results. We propose a method of measuring the importance and apply it to inequality variables in composite indices of development. The results show a low importance for most inequality variables, and for some of them, a large discrepancy between the nominal weights and the importance. We argue that the importance of variables should be considered in the process of index construction. This may imply a modification of the index when there is a large discrepancy between the nominal weights and importance and when the importance of some variables is extremely low. Whether any such modification is justified must be decided within the context of the particular index.

     

Weighted amplifiers and inapproximability results for Travelling Salesman problem

Journal of Combinatorial Optimization - The expander graph constructions and their variants are the main tool used in gap preserving reductions to prove approximation lower bounds of combinatorial...     

A Bivariate Beta-Gamma Autoregressive Process (BVBGAR(1))

In this article, we introduce a bivariate autoregressive process with Gamma marginal distributions using the form of the BGAR(2) process (Risti?, 2005 Risti? , M. M. ( 2005 ). A Beta-Gamma autoregressive process of the second-order (BGAR(2)) . Statist. Probab. Lett. 73 : 403 – 410 . [Google Scholar]) and the Beta-Gamma transformation. Some properties of the process such as the autocovariance matrix, the autocorrelation matrix, and the spectral density matrix are derived. The unknown parameters of the process are estimated using the method of moments and the method of conditional least squares. Some numerical results of the estimators are given. We investigate nonparametric and parametric estimation of the spectral density matrix of this process.