normal correlation
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2021 ◽  
Vol 29 (1) ◽  
pp. 50-66
Author(s):  
Shafiu Ibrahim Abdullahi

PurposeThe purpose of the study is to measure cross-country stock market correlation and volatility transmission during the global coronavirus disease 2019 (COVID-19) pandemic. The paper traces trajectory of Islamic equity investments in order to get insights on the behavior of the markets during the crisis.Design/methodology/approachThe paper uses generalized method of moments (GMM), autoregressive distributed lag (ARDL) and multivariate GARCH (MGARCH) models for analysis of dynamic causality, stock market cointegration, correlation and volatility transmission between Islamic stock indices.FindingsThe result of normal correlation analysis on the share indices show the markets move together. The result of ARDL cointegration test shows the markets returns are cointegrated as a group. To further make sense of the data; the indices were grouped into four different categories, then cointegration tests were conducted. The results of the analysis show that the subgroups are cointegrated except the low COVID-19 subgroup. Based on MGARCH findings, the possibility of volatility transmission between markets during the crisis is high. The market returns indices show the usual herd mentality common during the period of crisis.Originality/valueUnlike other works in this area, this paper attempt to trace the trajectory of Islamic equity investment in order to get relevant insights and arrives at appropriate ways of responding to the crisis.


2019 ◽  
Vol 23 (1) ◽  
pp. 148-152
Author(s):  
G.Y. Honcharenko

Adenomyosis (AD) is an urgent medical problem of the present. The issues of etiology and pathogenesis of internal endometriosis remain controversial. The purpose of the work is to define the role of estrogen (ER) and progesterone (PR) receptors in the pathogenesis of adenomyosis (AD) in postmenopausal women. Selection criteria: established diagnosis of AD, postmenopausal period (no menstruation for more than 1 year) and absence of concomitant endometrial pathology. An immunohistochemical (IHС) study was performed to determine the state of the receptor apparatus for markers of estrogen and progesterone. The IНC study of the eu- and ectopic endometrium receptor apparatus revealed the presence of ER and RR expression both in epithelial cells and stromal cells, indicating the hormonal dependence of AD foci and the key role of steroid hormones in the development and preservation of intraocular endometriosis in postmenopausal women. Nearly a third of women in the epithelial cells of the eutopic endometrium found a normal correlation between ER and PR, respectively leading to 1. In stromal cells, a decrease in ER was observed with an increase in RR (ER / PR <1) in 9 out of 15 patients. Analysis of the distribution of the ratio of expression ratios of ER and PR in ectopic endometrium revealed the predominance of the role of PR in ER in the pathogenesis of internal endometriosis. The components of the ectopic endometrium in most women were characterized by an increase in PR and a decrease in ER (ER / PR <1).


2018 ◽  
Author(s):  
Ricardo A. Valls

Compositional data arise naturally in several branches of science, including geology. In geochemistry, for example, these constrained data seem to occur typically, when one normalizes raw data or when one obtains the output from a constrained estimation procedure, such as parts per one, percentages, ppm, ppb, molar concentRations, etc. Compositional data have proved difficult to handle statistically because of the awkward constraint that the components of each vector must sum to unity. The special property of compositional data (the fact that the determinations on each specimen sum to a constant) means that the variables involved in the study occur in constrained space defined by the simplex, a restricted part of real space. Pearson was the first to point out dangers that may befall the analyst who attempts to interpret correlations between Ratios whose numerators and denominators contain common parts. More recently, Aitchison, Pawlowsky-Glahn, S. Thió, and other statisticians have develop the concept of Compositional Data Analysis, pointing out the dangers of misinterpretation of closed data when treated with “normal” statistical methods It is important for geochemists and geologists in general to be aware that the usual multivariate statistical techniques are not applicable to constrained data. It is also important for us to have access to appropriate techniques as they become available. This is the principal aim of this book. From a hypothetical model of a copper mineralization associated to a felsic intrusive, with specific relationships between certain elements, I will show how “normal” correlation methods fail to identify some of such embedded relationships and how we can obtain other spurious correlations. From there, I will test the same model after transforming the data using the CRL, ARL, and IRL transformations with the aid of the CoDaPack software. Since I addressed this publication to geologists and geoscientists in general, I have kept to a minimum the mathematical formulae and did not include any theoretical demonstRation. The “mathematical curios geologist”, if such category exists, can find all of those in a list of recommended sources in the reference section. So let us start by introducing the model of mineralization that we will be testing.


2016 ◽  
Vol 27 (2) ◽  
pp. 1-8
Author(s):  
A. Iqbal ◽  
L. Rahman ◽  
M. H. Kabir

The present research works were conducted to find out the variation in morphological traits and their relationship in Brassica materials at C7 (Colchiploid) alloplasmic populations and F5 generations with respect to their parents. Among the 19 Brassica progeny lines representing the cross products (Brassica napojuncea) of C7 generation of Brassica napus and Brassica juncea (BINA sharisha 5 x Daulot: colchiploid-C7) and F5 generations with their parents, inter-species EG2 (Brassica napus x Brassica juncea) and EG1 (Brassica napus x Brassica juncea) showed better agronomic performance. Phenotypic characters of the genotypes were closely associated with each other for both normal correlation coefficients and Spearman’s rank correlation coefficients. The total relative ranking ranged from 1 to 20 and the first rank was estimated for the genotype EG2 genotypes. The last rank was estimated for the genotype ED1 (Brassica napus x Brassica napus). Out of 55 associations, which found in the correlation study, 10 associations were found highly significant at the morphological level. Flower set per plant (self) showed highly significant positive association with total number of siliqua per plant (self) (r = 0.934**) but the significant negative association of the total number of siliqua per plant (self) with siliqua length was very strong (-0.489*). There was a genetic basis of association in most of the cases of pairs of relations. The Spearman’s rank correlation test was studied to compare the morphological characterization for distinguishing genotypes. In this present study, this test presented 12 relationships that showed 10 positive significant and two negative significant correlations. In normal correlation coefficients 10 significant associations were found but 12 associations in Spearman’s rank correlation. In these techniques, number of flower set per plant (self) had highly significant positive correlation with total number of siliqua per plant (rs = 0.817**). The days to 50 % flowering and number of seed per siliqua (self) had significant negative correlation with number of seed per siliqua (open) (rs = -0.546**) and number of flowers set per plant (open) (rs = -0.563*), respectively. Finally, the study suggested that some yield related traits such as flower set per plant, number of siliqua per plant, seed per siliqua and days to 50% flowering can be selected and used in breeding program for future increasing the grain yield of rapeseed.


2016 ◽  
Vol 39 (10) ◽  
pp. 1466-1485
Author(s):  
MF Kazemi ◽  
MA Pourmina ◽  
AH Mazinan

The present research attempts to address an automated optimization-based image-embedding approach through a levels-directions decomposition framework. The subject behind the present approach is to design colour image watermarking with a focus on contourlet representation, whereas the watermarking intensity is accurately calculated via an optimization algorithm with constraint. In the approach presented here, a number of performance monitors for watermarked and logo images are realized to deal with a new fitness function in the aforementioned optimization algorithm. It is worth noting that the first performance monitoring is organized based on the peak signal-to-noise ratio and the structural similarity, whereas the second one is organized based on the normal correlation and the bit error rate, respectively. There is a scrambling module to represent the logo information in disorder, where a number of attacks are simultaneously applied to the watermarked image in order to adjust the appropriate value for watermarking intensity to realize a robust and efficient solution. The ability of a decision maker system is manually taken into account for choosing the best levels and the corresponding directions regarding the contourlet representation, and the investigated results are considered in a number of well-known colour space models including RGB, YIQ and YCbCr. The key contribution of the present research is made based on the new integration of a set of subsystems employed in colour space models under the embedding and de-embedding processes in the contourlet representation, and the watermarking intensity is acquired through the optimization algorithm with constraint to present the competitive outcomes with respect to state-of-the-art benchmarks. The procedure for extracting the information concerning the logo image from the processed watermarked image under a number of attacks is implemented through the approach proposed, whereas there is no information about the original image and the watermarking intensity to be processed.


2012 ◽  
pp. 317-334
Author(s):  
G. Udny Yule
Keyword(s):  

2012 ◽  
pp. 313-330
Author(s):  
G. Undy Yule
Keyword(s):  

2011 ◽  
pp. 317-334
Author(s):  
G. Udny Yule
Keyword(s):  

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