Conditions for invariance of the multivariate versions of grubbs’ test and bartlett’s test under a general dependency structure

Metrika ◽  
1991 ◽  
Vol 38 (1) ◽  
pp. 83-97 ◽  
Author(s):  
R. Pavur ◽  
D. M. Young
2021 ◽  
Vol 13 (4) ◽  
pp. 60-77
Author(s):  
Maria Hudakova ◽  
Maria Gabrysova ◽  
Zora Petrakova ◽  
Katarina Buganova ◽  
Vladimir Krajcik

The aim of the paper is to assess the impact of the length of entrepreneurship on the perception of the most important business risks in Slovakia and the Visegrad Group of Countries (V4 countries). The empirical research was conducted in 2019-2020. It was focused on assessing the state of enterprise risk management (ERM) application. The research file contained 422 online questionnaires completed by owners and managers of enterprises (OMEs). The results of this case study were compared with the results of similar studies performed in the V4 countries in 2017-2018. In total, 1,781 OMEs participated in the surveys mentioned. The following statistical methods were used to assess the data: ANOVA, Bartlett’s test, Agostini test, good fit test, and Grubbs test. The overall results of the empirical research highlight the significance and importance of the assessment of business risks in the V4 countries. The results in Slovakia in 2019-2020 and the research results in the V4 countries in 2017-2018 show that OMEs still consider market and economic risks to be most important in their business. Market and economic risks are related to sources that exert the most negative influence on enterprise success. The results are valuable for entrepreneurs, enterprise managers and institutions that provide comprehensive entrepreneurship support in the V4 countries. The overall results are significant at the regional, national, and international levels of the V4 countries and have the ability to strengthen the competitiveness of entrepreneurs within the EU common market.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Mayssoon Dashash ◽  
Mounzer Boubou

Abstract Background Health professionals should have certain degree of empathy to eliminate the pain and suffering of their patients. There is a need to design a scale, which can assess empathy among health professionals and is relevant to community and culture. Therefore, this study was undertaken to measure the empathy among Syrian health professionals and students of health professions using a newly designed Syrian Empathy Scale that is relevant to community during Syrian crisis. Methods A cross-sectional observational study was undertaken. A total of 214 participants (118 males and 96 females) responded to the Syrian Empathy Scale SES from Medical (n = 62), Dental (n = 152). They were 59 undergraduates, 116 postgraduates and 39 general practitioners. The SES was designed as a tool that includes 20 items in a 7-point Likert-type scale with overall score ranges from 20 to 140. Group comparisons of the empathy scores were conducted using t-test and analysis of variance (ANOVA). A factor analysis was performed. Bartlett’s test of the sphericity and the KMO measure of sampling adequacy were also determined. Cronbach’s alpha was calculated. Results A significant difference was found between males and females in the SES mean score. The ANOVA analysis showed that the SES empathy scores of dentists were higher than the SES empathy scores in medical doctors with no significant difference. The SES empathy score of undergraduates was significantly higher than postgraduates and practitioners. Findings of KMO indicated sampling adequacy (KMO = 0.824 > 0.7) and the value of Bartlett’s test of the sphericity (1255.65, df = 190, P-value< 0.001) proved that the factor analysis is meaningful and acceptable. The results of varimax rotation proved that five main factors were retained. Conclusion Findings of this study support the reliability of the newly designed Syrian Empathy Scale for measuring empathy in the field of health care. The SES can be suggested for assessing empathy in different health educational programs. However, future works are still essential to support the validity of the scale as well as to ascertain the role of empathy in improving health care.


2020 ◽  
pp. 1-29
Author(s):  
Le Chang ◽  
Yanlin Shi

Abstract This paper investigates a high-dimensional vector-autoregressive (VAR) model in mortality modeling and forecasting. We propose an extension of the sparse VAR (SVAR) model fitted on the log-mortality improvements, which we name “spatially penalized smoothed VAR” (SSVAR). By adaptively penalizing the coefficients based on the distances between ages, SSVAR not only allows a flexible data-driven sparsity structure of the coefficient matrix but simultaneously ensures interpretable coefficients including cohort effects. Moreover, by incorporating the smoothness penalties, divergence in forecast mortality rates of neighboring ages is largely reduced, compared with the existing SVAR model. A novel estimation approach that uses the accelerated proximal gradient algorithm is proposed to solve SSVAR efficiently. Similarly, we propose estimating the precision matrix of the residuals using a spatially penalized graphical Lasso to further study the dependency structure of the residuals. Using the UK and France population data, we demonstrate that the SSVAR model consistently outperforms the famous Lee–Carter, Hyndman–Ullah, and two VAR-type models in forecasting accuracy. Finally, we discuss the extension of the SSVAR model to multi-population mortality forecasting with an illustrative example that demonstrates its superiority in forecasting over existing approaches.


2013 ◽  
Vol 45 (36) ◽  
pp. 5031-5045 ◽  
Author(s):  
Bruno P. Arruda ◽  
Pedro L. Valls Pereira

2016 ◽  
Vol 48 (1) ◽  
pp. 199-214
Author(s):  
Werner R. W. Scheinhardt ◽  
Dirk P. Kroese

Abstract We provide exact computations for the drift of random walks in dependent random environments, including k-dependent and moving average environments. We show how the drift can be characterized and evaluated using Perron–Frobenius theory. Comparing random walks in various dependent environments, we demonstrate that their drifts can exhibit interesting behavior that depends significantly on the dependency structure of the random environment.


2014 ◽  
Vol 22 (1) ◽  
pp. 3-15 ◽  
Author(s):  
Arkadiusz Bartczak ◽  
Ryszard Glazik ◽  
Sebastian Tyszkowski

Abstract The article presents the results of research into the transformation of series of hydro-meteorological data for determining dry periods with the Standardised Precipitation Index (SPI) and the Standardised Discharge Index (SDI). Time series from eight precipitation stations and five series of river discharge data in Eastern Kujawy (central Poland) were analysed for 1951–2010. The frequency distribution of the series for their convergence with the normal distribution was tested with the Shapiro–Wilk test and homogeneity with the Bartlett's test. The transformation of the series was done with the Box–Cox technique, which made it possible to homogenise the series in terms of variance. In Poland, the technique has never been used to determine the SPI. After the transformation the distributions of virtually all series complied with the normal distribution and were homogeneous. Moreover, a statistically significant correlation between the δ transformation parameter and the skewness of the series of monthly precipitation was observed. It was similar for the series of mean monthly discharges in the winter half-year and the hydrological year. The analysis indicates an alternate occurrence of dry and wet periods both in case of precipitation and run-offs. Drought periods coincided with low flow periods. Thus, the fluctuations tend to affect the development of agriculture more than long-term ones.


2016 ◽  
Vol 12 (S325) ◽  
pp. 259-262
Author(s):  
Susana Eyheramendy ◽  
Felipe Elorrieta ◽  
Wilfredo Palma

AbstractThis paper discusses an autoregressive model for the analysis of irregularly observed time series. The properties of this model are studied and a maximum likelihood estimation procedure is proposed. The finite sample performance of this estimator is assessed by Monte Carlo simulations, showing accurate estimators. We implement this model to the residuals after fitting an harmonic model to light-curves from periodic variable stars from the Optical Gravitational Lensing Experiment (OGLE) and Hipparcos surveys, showing that the model can identify time dependency structure that remains in the residuals when, for example, the period of the light-curves was not properly estimated.


2021 ◽  
Vol 9 (1A) ◽  
Author(s):  
Leticia Lins Ramos ◽  
César Marques Salgado ◽  
William Luna Salgado ◽  
Roos Sophia Dam ◽  
Francisco Oliveira Ferreira
Keyword(s):  


2015 ◽  
Vol 2 (1) ◽  
pp. 36-39
Author(s):  
C.R. Rinu Vasanth ◽  
P. Vignesh ◽  
R. Swapna Kuamri

In the current scenario quality control became mandatory for all the sectors .This study is intended to examine the impact of internet facilities on students’ performance through a Blended Learning as a medium in an academic institution. It was examined, how the Blended Learning encompasses a variety of tools to create flexible, rich learning environments that stimulate learners and maximizes the potential for learning? Another objective is Application of Six Sigma methodology in this study is to improve the medium of learning i.e. internet connectivity through a set of procedures in an effective way. Six Sigma can be again viewed as a discipline or an approach driven by data and methodology for eliminating defects in any process- from manufacturing to transactional and from product to service.Keeping the aforesaid two objectives in mind, data was collected from a sample of 119 students residing in various hostel blocks using stratified random sampling technique. Questionnaire was developed after an extensive literature review to measure the impact of internet connectivity in Blended Learning of the students. The questionnaire to measure was based on the model developed by Shawn M. Glynn (2011).The scale was developed by referring to previous models developed by various authors to measure the impact of internet connectivity in the Blended Learning of the students. The statistical analysis used was reliability statistics, KMO, Bartlett’s test and Factor Analysis. The data was analyzed by SPSS version 20). We observed that application of Six Sigma methodology is useful to improve the medium of learning.DOI: http://dx.doi.org/10.3126/ijssm.v2i1.11520     Int. J. Soc. Sci. Manage. Vol-2, issue-1: 36-39 


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