Statistics and Probability Commons^™

Adding Value To Numerical Weather Predictions For The Aviation Industry In South Africa., Quinton Jacobs Mr., Willem A. Landman Prof.

International Journal of Aviation, Aeronautics, and Aerospace

The main objective of this study is to determine whether human forecasters at the main airports of South Africa add value to the raw numerical weather prediction model output when they provide forecast services to the aviation industry. Dataset pairs of weather observations made at these airports and terminal aerodrome forecasts are constructed for three forecast systems: the human forecasters, persistence forecast and the raw output from the 12 km resolution Unified Model administered by the South African Weather Service. These three dataset pairs are independently evaluated by a forecast verification system developed at the South African Weather Service. A …

Cubic Rank Transmuted Modified Burr Iii Pareto Distribution: Development, Properties, Characterizations And Applications, Fiaz Ahmad Bhatti, Gholamhossein G. Hamedani, Wenhui Sheng, Munir Ahmad

Mathematical and Statistical Science Faculty Research and Publications

In this paper, a flexible lifetime distribution called Cubic rank transmuted modified Burr III-Pareto (CRTMBIII-P) is developed on the basis of the cubic ranking transmutation map. The density function of CRTMBIII-P is arc, exponential, left-skewed, right-skewed and symmetrical shaped. Descriptive measures such as moments, incomplete moments, inequality measures, residual life function and reliability measures are theoretically established. The CRTMBIII-P distribution is characterized via ratio of truncated moments. Parameters of the CRTMBIII-P distribution are estimated using maximum likelihood method. The simulation study for the performance of the maximum likelihood estimates (MLEs) of the parameters of the CRTMBIII-P distribution is carried out. …

The Zero Truncated Poisson Burr X Family Of Distributions With Properties, Characterizations, Applications, And Validation Test, T. H.M. Aboulemagd, Mohammed S. Hamed, Gholamhossein Hamedani, M. M. Ali, Hafida Goual, Mustafa Ç. Korkmaz, Haitham M. Yousof

Mathematical and Statistical Science Faculty Research and Publications

The goal of this work is to introduce a new family of continuous distributions with a strong physical application. Some statistical properties are derived, and certain useful characterizations of the proposed family distributions are presented. Five applications are provided to illustrate the importance of the new family. A modified goodness-of-fit test for the new family in complete data case are investigated via two examples. We propose, as a first step, the construction of Nikulin-Rao-Robson statistic based on chi-squared fit tests for the new family in the case of complete data. The new test is based on the Nikulin-Rao-Robson statistic separately …

การประยุกต์ใช้การเรียนรู้แบบเสริมกำลังกับการวางแผนทางการเงิน, ภัควัลย์ จันทรศิริภาส

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้มีวัตถุประสงค์ที่จะนำการเรียนรู้แบบเสริมกำลังมาประยุกต์กับการวางแผนทางการเงินเพื่อตัดสินใจเลือกอัตราส่วนของสินทรัพย์ที่ใช้ในการบริโภคและการลงทุนในสินทรัพย์ที่มีความเสี่ยงที่ดีที่สุดในแต่ละช่วงเวลาตลอดช่วงอายุของครัวเรือน ผลลัพธ์ที่ได้จากการเรียนรู้แบบเสริมกำลังซึ่งเป็นค่าประมาณ จะถูกนำมาเปรียบเทียบกับคำตอบที่ถูกต้องจากวิธี MDP สำหรับการเรียนรู้แบบเสริมกำลังในงานวิจัยนี้เป็นอัลกอริธึม SARSA โดยการเลือกการกระทำใช้วิธี ε-greedy ส่วนการประมาณค่าใช้ตัวแบบถดถอยที่มีตัวแปรต้นเป็นฟีเจอร์จากเคอร์เนล Radial Basis Function (RBF) จากการศึกษาพบว่าความผิดพลาดระหว่างค่าประมาณผลลัพธ์ที่ดีที่สุดเทียบกับคำตอบจาก MDP มีแนวโน้มลู่เข้าสู่ศูนย์ แสดงว่าการเรียนรู้แบบเสริมกำลังสามารถประยุกต์กับการวางแผนทางการเงินได้ อย่างไรก็ตาม SARSA แบบดั้งเดิมใช้เวลานานในการเรียนรู้ เมื่อปรับปรุงให้การเลือกการกระทำในช่วงแรกเน้นสำรวจมากขึ้น พบว่า ความผิดพลาดลดลง แสดงให้เห็นว่า SARSA ที่ปรับปรุงให้เน้นการสำรวจในช่วงแรกมีประสิทธิภาพดีขึ้นกว่าแบบดั้งเดิม นอกจากนี้เมื่อพิจารณาผลของการปรับเปลี่ยนปัจจัยต่างๆ สำหรับ SARSA แบบเน้นการสำรวจในช่วงแรก พบว่า ความผิดพลาดระหว่างค่าประมาณผลลัพธ์ที่ดีที่สุดเทียบกับ MDP มีค่าน้อยสุดเมื่อใช้ค่าน้ำหนักเริ่มต้นจากตัวแบบการถดถอยเชิงเส้น, จำนวนฟีเจอร์ 200 ลักษณะ, อัตราการเรียนรู้และความน่าจะเป็นในการเลือกการกระทำแบบสำรวจแบบลดลงตามเวลาที่มีค่าเริ่มต้น 0.1 และ 0.9 ตามลำดับ ในขณะที่การนำคำตอบที่ดีที่สุดไปจำลองใช้จริง ผลของการวางแผนทางการเงินที่ได้มีความแตกต่างกับคำตอบจาก MDP มาก โดยการใช้ค่าน้ำหนักเริ่มต้นจากตัวแบบการถดถอยเชิงเส้น, จำนวนฟีเจอร์ 300 ลักษณะ, อัตราการเรียนรู้และความน่าจะเป็นในการเลือกการกระทำแบบสำรวจแบบลดลงตามเวลาที่มีค่าเริ่มต้น 0.1 และ 0.9 ตามลำดับให้ผลลัพธ์ที่ใกล้เคียงกับ MDP มากสุด แสดงว่าถึงแม้ความผิดพลาดของผลลัพธ์ที่ดีที่สุดจะมีค่าต่ำสุด คำตอบจากวิธีการเรียนรู้แบบเสริมกำลังยังมีความผิดพลาดสูงเมื่อเทียบกับคำตอบจาก MDP

ความอยู่ดีมีสุขของวัยรุ่น: การวิเคราะห์อภิมานโมเดลสมการเชิงโครงสร้าง, นัฏฐิกา เจริญตะคุ

Chulalongkorn University Theses and Dissertations (Chula ETD)

การวิจัยครั้งนี้มีจุดประสงค์เพื่อ 1) ศึกษาตัวแปรคุณลักษณะงานวิจัย 3 ด้านคือ ด้านการตีพิมพ์ ด้านเนื้อหาสาระ และด้านวิธีวิทยาการวิจัยที่ส่งผลต่อขนาดอิทธิพลของความฉลาดทางอารมณ์ การรู้คุณ การสนับสนุนทางสังคม รูปแบบการเผชิญปัญหา และการสนับสนุนความเป็นอิสระที่ส่งผลต่อความอยู่ดีมีสุขของวัยรุ่น 2) สร้างและตรวจสอบโมเดลความสัมพันธ์เชิงสาเหตุของปัจจัยความฉลาดทางอารมณ์ การรู้คุณ การสนับสนุนทางสังคม รูปแบบการเผชิญปัญหา และการสนับสนุนความเป็นอิสระที่ส่งผลต่อความอยู่ดีมีสุขของวัยรุ่น ตัวอย่างที่ใช้ในการศึกษาครั้งนี้เป็นงานวิจัยสหสัมพันธ์เชิงสาเหตุเกี่ยวกับ ความอยู่ดีมีสุขของวัยรุ่นที่เผยแพร่ในรูปแบบบทความวิจัยในช่วงปี ค.ศ. 2007-2019 จำนวน 67 เรื่องจากทั้งหมด 61,696 เรื่อง โดยใช้การวิเคราะห์อภิมานโมเดลสมการเชิงโครงสร้างด้วยโปรแกรม R และ Mplus ผลการวิจัยมีดังนี้ 1. คุณลักษณะงานวิจัย 3 ด้านส่งผลต่อขนาดอิทธิพลของความฉลาดทางอารมณ์ การรู้คุณ รูปแบบการเผชิญปัญหา การสนับสนุนทางสังคม และการสนับสนุนความเป็นอิสระที่มีต่อความอยู่ดีมีสุขของวัยรุ่นโดยมีขนาดอิทธิพลเท่ากับ .23-.58 .19-.56 .19-.31 .20-.55 และ .20-.47 ตามลำดับ โดยขนาดอิทธิพลของแต่ละตัวแปรอิสระที่มีต่อความอยู่ดีมีสุขจะได้รับอิทธิพลจากคุณลักษณะงานวิจัยทั้ง 3 ด้านแตกต่างกัน 2. โมเดลความสัมพันธ์เชิงสาเหตุความอยู่ดีมีสุขของวัยรุ่นที่พัฒนาขึ้น ประกอบด้วยปัจจัย 4 ด้านคือ ความฉลาดทางอารมณ์ การสนับสนุนทางสังคม รูปแบบการเผชิญปัญหา และการรู้คุณ ซึ่งอธิบาย ความผันแปรของความอยู่ดีมีสุขได้ร้อยละ 18.3 โดยโมเดลดังกล่าวสอดคล้องกับข้อมูลเชิงประจักษ์ (χ2= 2.518; df= 1; p-value = .113; CFI = 1.000; TLI = 1.000; RMSEA = .006) ทั้งนี้ความฉลาดทางอารมณ์มีอิทธิพลต่อความอยู่ดีมีสุขของวัยรุ่นมากที่สุด รองลงมาคือ การรู้คุณ รูปแบบการเผชิญปัญหา และการสนับสนุนทางสังคม (.249 .245 .116 และ .141 ตามลำดับ)

Site- And Location-Adjusted Approaches To Adaptive Allocation Clinical Trial Designs, Brian S. Di Pace

Theses and Dissertations

Response-Adaptive (RA) designs are used to adaptively allocate patients in clinical trials. These methods have been generalized to include Covariate-Adjusted Response-Adaptive (CARA) designs, which adjust treatment assignments for a set of covariates while maintaining features of the RA designs. Challenges may arise in multi-center trials if differential treatment responses and/or effects among sites exist. We propose Site-Adjusted Response-Adaptive (SARA) approaches to account for inter-center variability in treatment response and/or effectiveness, including either a fixed site effect or both random site and treatment-by-site interaction effects to calculate conditional probabilities. These success probabilities are used to update assignment probabilities for allocating patients …

Methods For Evaluating Dropout Attrition In Survey Data, Camille J. Hochheimer

Theses and Dissertations

As researchers increasingly use web-based surveys, the ease of dropping out in the online setting is a growing issue in ensuring data quality. One theory is that dropout or attrition occurs in phases that can be generalized to phases of high dropout and phases of stable use. In order to detect these phases, several methods are explored. First, existing methods and user-specified thresholds are applied to survey data where significant changes in the dropout rate between two questions is interpreted as the start or end of a high dropout phase. Next, survey dropout is considered as a time-to-event outcome and …

Assessing The Impact Of Incorporating Residential Histories Into The Spatial Analysis Of Cancer Risk, Anny-Claude Joseph

Theses and Dissertations

In many spatial epidemiologic studies, investigators use residential location at diagnosis as a surrogate for unknown environmental exposures or as a geographic basis for assigning measured exposures. Inherently, they make assumptions about the timing and location of pertinent exposures which may prove problematic when studying long latency diseases such as cancer.

In this work we explored how the association between environmental exposures and disease risk for long-latency health outcomes like cancer is affected by residential mobility. We used simulation studies conditioned on real data to evaluate the extent to which the commonly held assumption of no residential mobility 1) affected …

Methods For Joint Normalization And Comparison Of Hi-C Data, John C. Stansfield

Theses and Dissertations

The development of chromatin conformation capture technology has opened new avenues of study into the 3D structure and function of the genome. Chromatin structure is known to influence gene regulation, and differences in structure are now emerging as a mechanism of regulation between, e.g., cell differentiation and disease vs. normal states. Hi-C sequencing technology now provides a way to study the 3D interactions of the chromatin over the whole genome. However, like all sequencing technologies, Hi-C suffers from several forms of bias stemming from both the technology and the DNA sequence itself. Several normalization methods have been developed for normalizing …

Latent Growth Model Approach To Characterize Maternal Prenatal Dna Methylation Trajectories, Dana Lapato

Theses and Dissertations

Background. DNA methylation (DNAm) is a removable chemical modification to the DNA sequence intimately associated with genomic stability, cellular identity, and gene expression. DNAm patterning reflects joint contributions from genetic, environmental, and behavioral factors. As such, differences in DNAm patterns may explain interindividual variability in risk liability for complex traits like major depression (MD). Hundreds of significant DNAm loci have been identified using cross-sectional association studies. This dissertation builds on that foundational work to explore novel statistical approaches for longitudinal DNAm analyses. Methods. Repeated measures of genome-wide DNAm and social and environmental determinants of health were collected up to six …

Genome-Wide Systems Genetics Of Alcohol Consumption And Dependence, Kristin Mignogna

Theses and Dissertations

Widely effective treatment for alcohol use disorder is not yet available, because the exact biological mechanisms that underlie this disorder are not completely understood. One way to gain a better understanding of these mechanisms is to examine the genetic frameworks that contribute to the risk for developing this disorder. This dissertation examines genetic association data in combination with gene expression networks in the brain to identify functional groups of genes associated with alcohol consumption and dependence.

The first study took advantage of the behavioral complexity of human samples, and experimental capabilities provided by mouse models, by co-analyzing gene expression networks …

Spectral Methods For The Detection And Characterization Of Topologically Associated Domains, Kellen Garrison Cresswell

Theses and Dissertations

The three-dimensional (3D) structure of the genome plays a crucial role in gene expression regulation. Chromatin conformation capture technologies (Hi-C) have revealed that the genome is organized in a hierarchy of topologically associated domains (TADs), sub-TADs, and chromatin loops which is relatively stable across cell-lines and even across species. These TADs dynamically reorganize during development of disease, and exhibit cell- and conditionspecific differences. Identifying such hierarchical structures and how they change between conditions is a critical step in understanding genome regulation and disease development. Despite their importance, there are relatively few tools for identification of TADs and even fewer for …

Statistical Designs For Network A/B Testing, Victoria V. Pokhilko

Theses and Dissertations

A/B testing refers to the statistical procedure of experimental design and analysis to compare two treatments, A and B, applied to different testing subjects. It is widely used by technology companies such as Facebook, LinkedIn, and Netflix, to compare different algorithms, web-designs, and other online products and services. The subjects participating in these online A/B testing experiments are users who are connected in different scales of social networks. Two connected subjects are similar in terms of their social behaviors, education and financial background, and other demographic aspects. Hence, it is only natural to assume that their reactions to online products …

Toward Using High-Frequency Coastal Radars For Calibration Of S-Ais Based Ocean Vessel Tracking Models, Ben Freidrich

Theses and Dissertations (Comprehensive)

Most of the world relies on ships for transportation, shipping, and tourism. Automatic Identification System messages are transmitted from ships and provide a wealth of positional data on these open ocean vessels. This data is being utilized to determine the optimal path for ships, as well as predicting where a ship may be going in the near future. It has only been in the past decade that Automatic Identification Systems (AIS) signals have been easily received with satellites (S-AIS) so there have been few studies that look at using available information and pairing it with the new abundance of ship …

Statistical Methods For Joint Analysis Of Multiple Phenotypes And Their Applications For Phewas, Xueling Li

Dissertations, Master's Theses and Master's Reports

Genome-wide association studies (GWAS) have successfully detected tens of thousands of robust SNP-trait associations. Earlier researches have primarily focused on association studies of genetic variants and some well-defined functions or phenotypic traits. Emerging evidence suggests that pleiotropy, the phenomenon of one genetic variant affects multiple phenotypes, is widespread, especially in complex human diseases. Therefore, individual phenotype analyses may lose statistical power to identify the underlying genetic mechanism. Contrasting with single phenotype analyses, joint analysis of multiple phenotypes exploits the correlations between phenotypes and aggregates multiple weak marginal effects and is therefore likely to provide new insights into the functional consequences …

Statistical Methods For Mixed Frequency Data Sampling Models, Yun Liu

Dissertations, Master's Theses and Master's Reports

The MIDAS models are developed to handle different sampling frequencies in one regression model, preserving information in the higher sampling frequency. Time averaging has been the traditional parametric approach to handle mixed sampling frequencies. However, it ignores information potentially embedded in high frequency. MIDAS regression models provide a concise way to utilize additional information in HF variables. While a parametric MIDAS model provides a parsimonious way to summarize information in HF data, nonparametric models would maintain more flexibility at the expense of the computational complexity. Moreover, one parametric form may not necessarily be appropriate for all cross-sectional subjects. This thesis …

Improved N-Dimensional Data Visualization From Hyper-Radial Values, Todd J. Paciencia, Trevor J. Bihl, Kenneth W. Bauer

Faculty Publications

Higher-dimensional data, which is becoming common in many disciplines due to big data problems, are inherently difficult to visualize in a meaningful way. While many visualization methods exist, they are often difficult to interpret, involve multiple plots and overlaid points, or require simultaneous interpretations. This research adapts and extends hyper-radial visualization, a technique used to visualize Pareto fronts in multi-objective optimizations, to become an n-dimensional visualization tool. Hyper-radial visualization is seen to offer many advantages by presenting a low-dimensionality representation of data through easily understood calculations. First, hyper-radial visualization is extended for use with general multivariate data. Second, a method …

On Burr Iii Marshal Olkin Family: Development, Properties, Characterizations And Applications, Fiaz Ahmad Bhatti, Gholamhossein G. Hamedani, Mustafa Ç. Korkmaz, Gauss M. Cordeiro, Haitham M. Yousof, Munir Ahmad

Mathematical and Statistical Science Faculty Research and Publications

In this paper, a flexible family of distributions with unimodel, bimodal, increasing, increasing and decreasing, inverted bathtub and modified bathtub hazard rate called Burr III-Marshal Olkin-G (BIIIMO-G) family is developed on the basis of the T-X family technique. The density function of the BIIIMO-G family is arc, exponential, left- skewed, right-skewed and symmetrical shaped. Descriptive measures such as quantiles, moments, incomplete moments, inequality measures and reliability measures are theoretically established. The BIIIMO-G family is characterized via different techniques. Parameters of the BIIIMO-G family are estimated using maximum likelihood method. A simulation study is performed to illustrate the performance of the …

On Burr Iii-Pareto Distribution: Development, Properties, Characterizations And Applications, Fiaz Ahmad Bhatti, Gholamhossein G. Hamedani, Mustafa Ç. Korkmaz, Munir Ahmad

Mathematical and Statistical Science Faculty Research and Publications

In this paper, a new four parameter lifetime model with increasing, decreasing, increasing-decreasing, decreasing-increasing-decreasing, modified bathtub, bathtub and inverted bathtub hazard rate function called Burr III-Pareto (BIII-Pareto) is developed on the basis of the T-X family technique. The BIII-Pareto density function is arc, J-shape, reverse J-shape, positively, negatively skewed and symmetrical. Some structural and mathematical properties including moments, moments of order statistics, inequality measures and reliability measures are theoretically established. The BIII-Pareto distribution is characterized via different techniques. Parameters of the BIII-Pareto distribution are estimated using maximum likelihood method. The simulation study for performance of the maximum likelihood estimates (MLEs) …

On The Modified Burr Xii-Power Distribution: Development, Properties, Characterizations And Applications, Fiaz Ahmad Bhatti, Gholamhossein G. Hamedani, Mustafa Ç. Korkmaz, Munir Ahmad

Mathematical and Statistical Science Faculty Research and Publications

In this paper, a flexible lifetime distribution with increasing, decreasing and bathtub hazard rate called the Modified Burr XII-Power (MBXII-Power) is developed on the basis of the T-X family technique. The density function of the MBXII-Power is arc, exponential, left-skewed, right-skewed, J, reverse-J and symmetrical shaped. Descriptive measures such as moments, moments of order statistics, incomplete moments, inequality measures, residual life functions and reliability measures are theoretically established. The MBXII-Power distribution is characterized via different techniques. Parameters of the MBXII-Power distribution are estimated using maximum likelihood method. The simulation study is performed on the basis of graphical results to see …

Does It Take Three To Dance The Tango? Organizational Design, Triadic Structures And Boundary Spanning Across Subunits, Stefano Tasselli, Alberto Caimo

Articles

In this paper, we investigate the processes of boundary spanning across subunits within organizational networks. We hypothesize that patterns of advice across organizational subunits are explained by different triadic mechanisms depending on the organizational design of the intra-organizational network. In organizational networks characterized by flat hierarchy, we found triadic cyclic closure to be positively associated to boundary spanning across subunits; but when the network reflects an organizational structure with formal hierarchical differentiation among members, then we found triadic transitive closure to be associated to boundary spanning across subunits. We test these predictions in two empirical studies consisting of two organizational …

A Multilayer Exponential Random Graph Modelling Approach For Weighted Networks, Alberto Caimo, Isabella Gollini

Articles

A new modelling approach for the analysis of weighted networks with ordinal/polytomous dyadic values is introduced. Specifically, it is proposed to model the weighted network connectivity structure using a hierarchical multilayer exponential random graph model (ERGM) generative process where each network layer represents a different ordinal dyadic category. The network layers are assumed to be generated by an ERGM process conditional on their closest lower network layers. A crucial advantage of the proposed method is the possibility of adopting the binary network statistics specification to describe both the between-layer and across-layer network processes and thus facilitating the interpretation of the …

On The Generalized Log Burr Iii Distribution: Development, Properties, Characterizations And Applications, Fiaz Ahmad Bhatti, Gholamhossein Hamedani, Azeem Ali, Munir Ahmad

Mathematical and Statistical Science Faculty Research and Publications

In this paper, we present a generalized log Burr III (GLBIII) distribution developed on the basis of a generalized log Pearson differential equation (GLPE). The density function of the GLBIII is exponential, arc, J, reverse-J, bimodal, left-skewed, right- skewed and symmetrical shaped. The hazard rate function of GLBIII distribution has various shapes such as constant, increasing, decreasing, increasing-decreasing, upside- down bathtub and modified bathtub. Descriptive measures such as quantile function, sub- models, ordinary moments, moments of order statistics, incomplete moments, reliability and uncertainty measures are theoretically established. The GLBIII distribution is characterized via different techniques. Parameters of the GLBIII distribution …

A New Extension Of Lindley Distribution: Modified Validation Test, Characterizations And Different Methods Of Estimation, Mohamed Ibrahim, Abhimanyu Singh Yadav, Haitham M. Yousof, Hafida Goual, Gholamhossein Hamedani

Mathematical and Statistical Science Faculty Research and Publications

In this paper, a new extension of Lindley distribution has been introduced. Certain characterizations based on truncated moments, hazard and reverse hazard function, conditional expectation of the proposed distribution are presented. Besides, these characterizations, other statistical/mathematical properties of the proposed model are also discussed. The estimation of the parameters is performed through different classical methods of estimation. Bayes estimation is computed under gamma informative prior under the squared error loss function. The performances of all estimation methods are studied via Monte Carlo simulations in mean square error sense. The potential of the proposed model is analyzed through two data sets. …

Statistical Modeling Of Influenza-Like-Illness In Montana Using Spatial And Temporal Methods, Benjamin A. Stark

Graduate Student Theses, Dissertations, & Professional Papers

Studying air pollution and public health has been a historically important question in science. It has long been hypothesized that severe air pollution conditions lead to negative implications in basic human health. Primarily, areas thats are prone to severe degrees of human pollution are the focus of such studies. Such research relating to less populated areas are scarce, and this scarcity raises the question of how such pollution dynamics (human-made and natural) influence human health in more rural areas.

The aim of this study is to explore this hole in research; in particular we explore possible links between air pollution …

Colloidal And Truly Dissolved Metal(Loid)S In Wastewater Lagoons And Their Removal With Floating Treatment Wetlands, Lauren Sullivan

Graduate Student Theses, Dissertations, & Professional Papers

Climate change is predicted to cause continuing declines in late-season streamflow, thus increasing the relative contribution of wastewater effluent to surface water flows. Wastewater effluent represents a critical point source of metal and metalloid contamination to aquatic ecosystems and wastewater lagoons are the most common wastewater treatment system in the rural United States. Although the fraction of total wastewater metals and metalloids in "dissolved" forms (defined here asnm) likely drives the potential for negative effects on receiving waters, this broad operational definition lumps truly dissolved solutes (nm) with small colloids and nanomaterials (1-450 nm; hereafter colloids). This size distinction may …