Search results for "Hypothesis"
showing 10 items of 426 documents
Beyond the functional matrix hypothesis: a network null model of human skull growth for the formation of bone articulations.
2014
Craniofacial sutures and synchondroses form the boundaries among bones in the human skull, providing functional, developmental and evolutionary information. Bone articulations in the skull arise due to interactions between genetic regulatory mechanisms and epigenetic factors such as functional matrices (soft tissues and cranial cavities), which mediate bone growth. These matrices are largely acknowledged for their influence on shaping the bones of the skull; however, it is not fully understood to what extent functional matrices mediate the formation of bone articulations. Aiming to identify whether or not functional matrices are key developmental factors guiding the formation of bone articu…
Time Series Momentum in the US Stock Market: Empirical Evidence and Theoretical Implications
2020
There is much controversy in the academic literature on the presence of short-term trends in financial markets and the trend-following strategy's profitability. This paper restricts its attention to the study of time-series momentum (TSMOM) in the US stock market. The paper aims to suggest answers to several important questions regarding TSMOM and to explain the existing controversy. Our answer to the question, whether short-term trends exist, is strongly affirmative. For the first time, we suppose that the returns follow a p-order autoregressive process with p>1 and evaluate this process's parameters. Fairly accurate knowledge of the momentum generating process allows us to provide analyti…
New chronology for Ksâr ‘Akil (Lebanon) supports Levantine route of modern human dispersal into Europe
2015
Modern human dispersal into Europe is thought to have occurred with the start of the Upper Paleolithic around 50,000-40,000 y ago. The Levantine corridor hypothesis suggests that modern humans from Africa spread into Europe via the Levant. Ksâr 'Akil (Lebanon), with its deeply stratified Initial (IUP) and Early (EUP) Upper Paleolithic sequence containing modern human remains, has played an important part in the debate. The latest chronology for the site, based on AMS radiocarbon dates of shell ornaments, suggests that the appearance of the Levantine IUP is later than the start of the first Upper Paleolithic in Europe, thus questioning the Levantine corridor hypothesis. Here we report a seri…
Technological differences and convergence in the OECD
2000
Abstract. In this paper we test the homogeneity of the technological parameters among OECD countries, which is the maintained hypothesis in most of the empirical growth literature. We first identify differences in the constant term of the convergence equation estimated for the OECD 1960/1990 sample using a fixed- effects estimator. Then we provide a formal test of the homogeneity of technological parameters across groups of countries. We identify at least two different groups within the OECD, with significantly different technologies. Convergence within each group is fast, supporting the notion of club convergence. Nevertheless, the implausible parameter values obtained for the leading tech…
FRACTALITY EVIDENCE AND LONG-RANGE DEPENDENCE ON CAPITAL MARKETS: A HURST EXPONENT EVALUATION
2014
Since the existence of market memory could implicate the rejection of the efficient market hypothesis, the aim of this paper is to find any evidence that selected emergent capital markets (eight European and BRIC markets, namely Hungary, Romania, Estonia, Czech Republic, Brazil, Russia, India and China) evince long-range dependence or the random walk hypothesis. In this paper, the Hurst exponent as calculated by R/S fractal analysis and Detrended Fluctuation Analysis is our measure of long-range dependence in the series. The results reinforce our previous findings and suggest that if stock returns present long-range dependence, the random walk hypothesis is not valid anymore and neither is…
Interval Length Analysis in Multi Layer Model
2009
In this paper we present an hypothesis test of randomness based on the probability density function of the symmetrized Kulback-Leibler distance estimated, via a Monte Carlo simulation, by the distributions of the interval lengths detected using the Multi-Layer Model (MLM). The $MLM$ is based on the generation of several sub-samples of an input signal; in particular a set of optimal cut-set thresholds are applied to the data to detect signal properties. In this sense MLM is a general pattern detection method and it can be considered a preprocessing tool for pattern discovery. At the present the test has been evaluated on simulated signals which respect a particular tiled microarray approach …
Comparing local structures of spatio-temporal point processes on linear networks
2022
We employ the Local Indicators of Spatio-Temporal Association (LISTA) functions on linear networks to build a statistical test for local second-order structure. This allows to identify differences in the spatio-temporal clustering behaviour of two point patterns, a point pattern of interest and a background one, both occurring on the same linear network. We illustrate the proposed methodology analysing a traffic-related problem.
A novel sequential testing procedure for selecting the number of changepoints in segmented regression models
2023
In this work, we address the problem of selecting the number of changepoints in segmented regression models. We propose a novel stepwise procedure and assess its performance through simulation studies. We demonstrate that our proposal behaves well with the Gaussian and Binomial responses.
Carbon and inflation
2021
Abstract This paper investigates whether European Union Allowances (EUAs) can serve as an inflation hedge for two economic areas, four euro countries and two non-euro countries. The Extended Fisher Hypothesis is tested and the evidence shows a strong positive relationship between EUA returns and the unexpected inflation component in all the economic areas or countries analysed, except for the US. Therefore, EUAs are able to provide a hedge against unanticipated inflation rates.
US stock market sensitivity to interest and inflation rates: a quantile regression approach
2016
ABSTRACTThis article studies the sensitivity of the US stock market to nominal and real interest rates and inflation during the 2003–2013 period using quantile regression (QR). The empirical results show that the stock market has a significant sensitivity to changes in interest rates and inflation and finds differences across sectors and over time. Moreover, the effect of changes in both interest rates and inflation tends to be more pronounced during extreme market conditions, thus distinguishing expansion periods from recession periods.