Search results for "statistical [methods]"
showing 10 items of 1664 documents
Inferring slowly-changing dynamic gene-regulatory networks
2015
Dynamic gene-regulatory networks are complex since the interaction patterns between their components mean that it is impossible to study parts of the network in separation. This holistic character of gene-regulatory networks poses a real challenge to any type of modelling. Graphical models are a class of models that connect the network with a conditional independence relationships between random variables. By interpreting these random variables as gene activities and the conditional independence relationships as functional non-relatedness, graphical models have been used to describe gene-regulatory networks. Whereas the literature has been focused on static networks, most time-course experi…
Feigenbaum graphs: a complex network perspective of chaos
2011
The recently formulated theory of horizontal visibility graphs transforms time series into graphs and allows the possibility of studying dynamical systems through the characterization of their associated networks. This method leads to a natural graph-theoretical description of nonlinear systems with qualities in the spirit of symbolic dynamics. We support our claim via the case study of the period-doubling and band-splitting attractor cascades that characterize unimodal maps. We provide a universal analytical description of this classic scenario in terms of the horizontal visibility graphs associated with the dynamics within the attractors, that we call Feigenbaum graphs, independent of map…
Testing alternative vicariance scenarios in Western Mediterranean discoglossid frogs
2004
Dated molecular phylogenies are often used to interpret evolutionary history with respect to paleogeographic events. Where more than one interpretation is possible, it is desirable but difficult to assess the alternatives in an objective manner. The present work demonstrates a formalized method for testing molecular clock calibrations and biogeographic scenarios based on them. We assessed the plausibility of several previously published biogeographic hypotheses, using the frog genera Alytes, Discoglossus, and Bombina as model groups. Our data set comprised ca. 900bp of partial mitochondrial 16S and 12S rRNA gene sequences (both genes evolved in a clock-like manner across genera) from nearly…
Polarization and suburbanisation in Warsaw
2001
The economic transition in Poland leads to a restructuration of economic activities which affects spatial patterns of cities, especially in Warsaw. Analyzing the location and re-location of population and employment in Poland’s capital allows to enlarge the debate on the suburbanization forms to the Central and Oriental European Countries. The results support the fact that the city center is still largely the most important district in terms of population andemployment, so that in 1999 the city keeps a strong monocentric character. However, from 1994 to 1999, population and employment move towards the Warsaw’s suburbs. Two significant observations, namely the suburbanization of retailing an…
Third Sector, Social Enterprises and Local Authorities in a EU Candidate Country. The Case of Albania
2013
The paper is based on evidence offered by survey data collected through a structured questionnaire in a long range survey launched in July 2012 by the Steering Group of ASE Forum. The aim of the study was to reveal the trend, status, profile, features and the role of potentials enterprises in Albania in supporting welfare and wellbeing in synergy with the local authorities.After an appropriate methodological introduction, the paper reports main statistical evidence concerning the Third sector in Albania and the direct survey outcomes about the features and the activity of the organizations interviewed.Conclusions will be driven by data analysis and will be focused on the needs, limits and o…
Quantitative Characteristics of Information Society and ICT Industry in Latvia
2015
Abstract The article is devoted to statistical analysis of information and communication technology (ICT) industry in Latvia and the development of Information Society in the country. On the basis of statistical data comparison of Latvia with other European countries is made. This comparison shows that Latvia belongs to countries with very well developed Internet. On the other hand the statistical data points on the fact that it is necessary to increase the awareness of population regarding possibilities offered by using of ICT and e-Government.
Dealing with preference uncertainty in contingent willingness to pay for a nature protection program: A new approach
2013
In this paper, we propose an alternative preference uncertainty measurement approach where respondents have the option to indicate their willingness to pay (WTP) for a nature protection program either as exact values or intervals from a payment card, depending on whether they are uncertain about their valuation. On the basis of their responses, we then estimate their degree of uncertainty. New within this study is that the respondent's degree of uncertainty is "revealed", while it is "stated" in those using existing measurement methods. Three statistical models are used to explore the sources of respondent uncertainty. We also present a simple way of calculating the uncertainty adjusted mea…
Do firms share the same functional form of their growth rate distribution? A statistical test
2014
We introduce a new statistical test of the hypothesis that a balanced panel of firms have the same growth rate distribution or, more generally, that they share the same functional form of growth rate distribution. We applied the test to European Union and US publicly quoted manufacturing firms data, considering functional forms belonging to the Subbotin family of distributions. While our hypotheses are rejected for the vast majority of sets at the sector level, we cannot rejected them at the subsector level, indicating that homogenous panels of firms could be described by a common functional form of growth rate distribution.
Variable selection in the analysis of energy consumption-growth nexus
2015
There is abundant empirical literature that focuses on whether energy consumption is a critical driver of economic growth. The evolution of this literature has largely consisted of attempts to solve the problems and answer the criticisms arising from earlier studies. One of the most common criticisms is that previous work concentrates on the bivariate relationship, energy consumption–economic growth. Many authors try to overcome this critique using control variables. However, the choice of these variables has been ad hoc, made according to the subjective economic rationale of the authors. Our contribution to this literature is to apply a robust probabilistic model to select the explanatory …
Inference for Lorenz curve orderings
1999
In this paper we consider the issue of performing statistical inference for Lorenz curve orderings. This involves testing for an ordered relationship in a multivariate context and making comparisons among more than two population distributions. Our approach is to frame the hypotheses of interest as sets of linear inequality constraints on the vector of Lorenz curve ordinates, and apply order-restricted statistical inference to derive test statistics and their sampling distributions. We go on to relate our results to others which have appeared in recent literature, and use Monte Carlo analysis to highlight their respective properties and comparative performances. Finally, we discuss in gener…