40 research outputs found
Permutation multivariate tests for treatment effect: theory and recent debelopments
No full textWhen the effect of a treatment is evaluated according to several outcomes, a suitable multivariate test must be applied. When the number of response variables is very large, especially in the presence of a small number of patients, typical multivariate parametric solutions (such as Hotelling T-square test) are not possible. As a motivating example, we consider a randomized controlled trial to test the effectiveness of a specific myotensive technique
Advances on Permutation Multivariate Analysis of Variance for big data
No full textIn many applications of the multivariate analyses of variance, the classic parametric solutions for testing hypotheses of equality in population means or multisample and multivariate location problems might not be suitable for various reasons. Multivariate multisample location problems lack a comparative study of the power behaviour of the most important combined permutation tests as the number of variables diverges. In particular, it is useful to know under which conditions each of the different tests is preferable in terms of power, how the power of each test increases when the number of variables under the alternative hypothesis diverges, and the power behaviour of each test as the function of the proportion of true alternative hypotheses. The purpose of this paper is to fill the gap in the literature about combined permutation tests, in particular for big data with a large number of variables. A Monte Carlo simulation study was carried out to investigate the power behaviour of the tests, and the application to a real case study was performed to show the utility of the method
Nonparametric Method for MUltivariate Tests with Big Data
No full textIn several testing problems we have big datasets. For instance, we could have a large number of response variables. Parametric methods, such as Hotelling T-square test, cannot be applied when the number of outcomes is greater than the sample sizes. Furthermore, strong assumptions such as homoskedasticity and normality are not plausible. We focus on two-sample multivariate problems and propose a nonparametric solution based on a permutation test
Complex hypothesis testing on Circular Economy
No full textWe propose nonparametric solutions within the family of combined permutation tests for testing complex hypothesis concerning Circular Econom
Review about the Permutation Approach in Hypothesis Testing
No full textToday, permutation tests represent a powerful and increasingly widespread tool of statistical inference for hypothesis-testing problems. To the best of our knowledge, a review of the application of permutation tests for complex data in practical data analysis for hypothesis testing is missing.
In particular, it is essential to review the application of permutation tests in two-sample or multisample problems and in regression analysis. The aim of this paper is to consider the main scientific contributions on the subject of permutation methods for hypothesis testing in the mentioned fields.
Notes on their use to address the problem of missing data and, in particular, right-censored data, will also be included. This review also tries to highlight the limits and advantages of the works cited with a critical eye and also to provide practical indications to researchers and practitioners who need to identify flexible and distribution-free solutions for the most disparate hypothesis-testing problems
Nonparametric hypothesis testing for multivariate and complex data on sustainability
No full textThe dissertation comprises three chapters, in which the whole thesis focuses on the nonparametric solution for hypothesis testing of multivariate and complex datasets. The complexity of the dataset includes in particular the violation of parametric assumptions, small sample size, one-sided alternative hypothesis, and missing data. In the second chapter, we review about permutation test for analyzing complex datasets. We attempt to figure out the limitation of the previous studies and suggest some possible remedies. In chapter 3, we study the power performance and asymptotic properties of the combined permutation test (CPT) for complex data. The simulation results reveal that the CPT is the only nonparametric solution to tackle the loss of degrees of freedom when the number of response variables is greater than the sample size. For the two-sample test, the most powerful CPT is based on the Tippett combination when the percentage of true partial alternative hypotheses is ≤30%, that based on the Fisher combination when the percentage is, >30% and <100%, and that based on the Liptak combination when the percentage is 100. Finally, we analyzed the multidimensional sustainable development goals in Ethiopia using CPT. Moreover, we advance the power behavior of the CPT for multivariate analysis of variance, especially for the ``big dataset". The simulation proves that the power of CPT increases as the number of samples and variables of the dataset increases. Besides, the proportion of true partial alternative hypotheses is more vital than the absolute number of variables in explaining the power improvement of CPT. Finally, we apply the CPT to study the organizational well-being of University workers. In chapter 4, we propose CPT for testing the significance of coefficients of the multivariate linear regression model. The simulation results prove that the proposed CPT is exact, unbiased, and consistent to test the significance of coefficients. The power of CPT increases as the number of dependent variables increases with fixed sample size. We applied the CPT to analyze multidimensional private firm performance in Ethiopia. Finally, chapter 5 consists of the summary of findings and future research work guidelines
Satisfaction and associated factors of outpatient psychiatric service consumers in Ethiopia
No full textSolomon Yimer,1 Zegeye Yohannis,2 Wondale Getinet,3 Tesfa Mekonen,4 Wubalem Fekadu,4 Habte Belete,4 Melak Menberu,5 Asmamaw Getnet,6 Amsalu Belete7 1Psychiatry Department, College of Health Sciences and Medicine, Dilla University, Dilla, 2Amanuel Mental Specialized Hospital, Addis Ababa, 3Psychiatry Department, College of Health Science and Medicine, University of Gondar, Gondar, 4Psychiatry Department, College of Medicine and Health Sciences, Bahir Dar University, Bahir Dar, 5Department of Nursing, College of Health Sciences, Mizan-Tepi University, Mizan, 6Finote Selam Hospital, Finote Selam, 7Department of Nursing, College of Health Sciences and Medicine, Debre Tabor University, Debre Tabor, Ethiopia Purpose: The purpose of this study was to assess the level of patient satisfaction and associated factors with psychiatric outpatient services in Ethiopia.Patients and methods: A cross-sectional study was performed from May 2015 to June 2015. A total of 454 participants selected by systematic random sampling were included in this study. Pretested and interviewer-administered questionnaire was used to collect the data. Patient satisfaction was measured using Charleston Psychiatric Outpatient Satisfaction Scale, and other validated tools were used to assess the associated variables. Multivariate logistic regressions with 95% confidence interval (CI) were used to assess the strength, and P-value <0.05 was used to indicate significance of association.Results: A total of 441 respondents were enrolled, with a response rate of 97.1% and magnitude of satisfaction of 61.2%. Being male (adjusted odds ratio [AOR] =0.612, 95% CI: 0.39, 0.94), being widowed (AOR =0.13, 95% CI: 0.05, 0.36), urban residence (AOR =0.49, 95% CI: 0.31, 0.78), diagnosed with schizophrenia (AOR =0.48, 95% CI: 0.28, 0.81), unfavorable attitude (AOR =0.49, 95% CI: 0.28, 0.86), and poor social functioning (AOR =0.52, 95% CI: 0.34, 0.80) were significantly associated with satisfaction.Conclusion: More than one-third of psychiatric service consumers were dissatisfied with the service they received. Integrating patients to their own treatment plan and regular service evaluation are important to improve satisfaction. Keywords: patient satisfaction, mental illness, social functionin
Review about the Permutation Approach in Hypothesis Testing
No full textToday, permutation tests represent a powerful and increasingly widespread tool of statistical inference for hypothesis-testing problems. To the best of our knowledge, a review of the application of permutation tests for complex data in practical data analysis for hypothesis testing is missing. In particular, it is essential to review the application of permutation tests in two-sample or multi-sample problems and in regression analysis. The aim of this paper is to consider the main scientific contributions on the subject of permutation methods for hypothesis testing in the mentioned fields. Notes on their use to address the problem of missing data and, in particular, right-censored data, will also be included. This review also tries to highlight the limits and advantages of the works cited with a critical eye and also to provide practical indications to researchers and practitioners who need to identify flexible and distribution-free solutions for the most disparate hypothesis-testing problems
Security challenges in the transition to 4G mobile systems in developing countries
No full textAbstract4 G mobile networks have evolved to meet the ever-increasing demand and requirements of users. 4 G will provide comprehensive IP solutions, allowing users to access voice, data, and streaming multimedia services at any time, from any location. Nonetheless, this transition will introduce new vulnerabilities and threats to service providers and customers. With the introduction of machine-to-machine (M2M) communication and the Internet of Things (IoT), malicious actors now have more attack ground. Attackers have an easier time sneaking into 4 G networks in developing countries because outdated and unprotected devices are still in use. Many startups and individuals did not invest in protecting their devices, owing to financial constraints and a lack of fundamental cyber security awareness. Because many network devices in developing countries are old and poorly protected, they could serve as a launching pad for perpetrators. This work thoroughly investigates and discusses fundamental security flaws in the 4 G network. These flaws could provide a path for malicious actors. Several factors exist in developing countries that expose them to perpetrators have been explained and elaborated on this work. Additionally, potential solutions to combat these issues are proposed
Design and Optimization of Wideband Rectangular-Framed Pi-Shaped mmWave Antenna Array for 5G Applications
No full textRecent applications like mmWave technologies require antenna characteristics such as high gain and wide bandwidth for smooth operation with high speed. Hence, this paper presents a novel pi-shaped patch antenna framed within a square structure for mmWave applications at 28 GHz. In the process of designing a four-element linear-planar antenna array (LPAA), a thin single antenna element is designed on a 0.275 mm Rogers 5880 substrate with a dielectric constant of 2.2. The proposed single-element antenna provides a gain of 3 dBi at 28 GHz and a wide impedance bandwidth ranging from 22.482 GHz to 40.511 GHz. Then, this proposed structure is transformed into a four-element LPAA with a compact dimension of 0.263 mm × 18.55 mm × 23.99 mm. To enhance and predict the impedance bandwidth of the proposed LPAA, mathematical modeling using response surface methodology and constrained numerical optimization is applied. In the optimization process of the antenna, independent factors such as substrate height (Hs) and interelement spacing (d) that influence the antenna’s responses such as impedance bandwidth (BW) and operating frequency (Fr) are considered. These factors are varied repeatedly and simulated using computer simulation technology (CST) suite 2019 for preparing the dataset, which is used as an input for mathematical modeling. Then, response surface methodology (RSM) is employed to relate the responses with independent factors. Models are validated using analysis of variance (ANOVA). The optimum parameters determined by applying constrained numerical optimization are substrate height (Hs) and interelement spacing (d) of values 0.263 mm and 5.61 mm, respectively. The optimized LPAA provides a wide bandwidth of 11 GHz and a peak gain of 9.25 dBi. The antenna also gives radiation efficiency of ≥98.5% and VSWR of less than 2 in its operating frequency range. The results included here are simulated using the CST EM solver and validated using the Ansys High-Frequency Simulation Software (HFSS). The proposed antenna provides high gain and wide bandwidth, which makes it a good candidate for 5G wireless communication applications
