Differential item functioning (DIF) detection rates were examined for the logistic regression and analysis of variance (ANOVA) DIF detection methods. The methods were applied to simulated data sets of varying test length (20, 40, and 60 items) and sample size (200, 400, and 600 examinees) for both equal and unequal underlying ability between groups as well as for both fixed and varying item discrimination parameters. Each test contained 5% uniform DIF items, 5% non-uniform DIF items, and 5% combination DIF (simultaneous uniform and non-uniform DIF) items. The factors were completely crossed, and each experiment was replicated 100 times. For both methods and all DIF types, a test length of 20 was sufficient for satisfactory DIF detection. The detection rate increased significantly with sample size for each method. With the ANOVA DIF method and uniform DIF, there was a difference in detection rates between discrimination parameter types, which favored varying discrimination and decreased with increased sample size. The detection rate of non-uniform DIF using the ANOVA DIF method was higher with fixed discrimination parameters than with varying discrimination parameters when relative underlying ability was unequal. In the combination DIF case, there was a three-way interaction among the experimental factors discrimination type, relative ability, and sample size for both detection methods. The error rate for the ANOVA DIF detection method decreased as test length increased and increased as sample size increased. For both methods, the error rate was slightly higher with varying discrimination parameters than with fixed. For logistic regression, the error rate increased with sample size when relative underlying ability was unequal between groups. The logistic regression method detected uniform and non-uniform DIF at a higher rate than the ANOVA DIF method. Because the type of DIF present in real data is rarely known, the logistic regression method is recommended for most cases.

This study aims to investigate the determinants of capital structure in small and medium-sized enterprises (SMEs) in Malaysia and their effect on firms’ performance. The study addresses the following primary question: What are the factors that influence the capital structure of SMEs in Malaysia? The sample of this research is SMEs in the east coast region of Malaysia. Adopting a positivist paradigm, the research design includes a preliminary study comprising 25 interviews with the owner-managers of SMEs, which is analysed using thematic analysis. The results are used to finalise the conceptual framework for the main study, which takes the form of a self-completion questionnaire survey. Usable responses were received from 384 firms, giving a response rate of 75.3%. The survey data is analysed using a series of binomial logistic regression models. Results reveal that there was no indication for the impact of owner’s education and experience on capital structure decisions. Other owner-related factors, firm characteristics, management performance and environment were found to relate to all types of capital structure. Both complete and partial mediating effects are also discovered in this study. The results provide evidence to support the pecking order hypothesis (Myers, 1984; Myers and Majluf, 1984), agency theory (Jensen and Meckling, 1976) and culture model of Schwartz (1994). It appeared that owner-managers in Malaysia do not strive to adjust their capital structure towards some optimal debt ratio, which is contrary to the static trade-off theory (DeAngelo and Masulis, 1980) of capital structure. This study makes several important contributions to the existing studies of capital structure. This research led to the development of a model of capital structure determinants by integrating factors related to owner-managers, firms, culture, and environment. This study incorporates methodological triangulation that may mitigate the problem of the difficulties in accessing financial data of SMEs in Malaysia. This study also provides meaningful insight into the financing preferences of the owner-managers with relevant implementations to academics, business practitioners, financial providers and policymakers. The research findings should assist owner-managers in making optimal capital structure decisions as well as help the policymaker in making an appropriate policy on the financing.

The more enhanced and reliable healthcare facilities, depend partly on accumulated organizational knowledge. Ontology and semantic web are the key factors in long-term sustainability towards the improvement of patient treatment process. Generally, researchers have the common consensus that knowledge is hard to capture due to its implicit nature, making it hard to manage. Medical professionals spend more time on getting the right information at the right moment, which is already available on intranet/internet. Evaluating the literature is controversial but interesting debates on ontology and semantic web encouraged us to propose a method and 4-Tier Architecture for retrieving context-based document according to user’s information in healthcare organization. Medical professionals are facing problems to access relevant information and documents for performing different tasks in the patient-treatment process. We have focused to provide context-based retrieval of documents for medical professionals by developing a semantic web solution. We also developed different OWL ontology models, which are mainly used for semantic tagging in web pages and generating context to retrieve the relevant web page documents. In addition, we developed a prototype to testify our findings in health care sector with the goal of retrieving relevant documents in a practical manner. / E-Health

El objetivo del presente trabajo de investigación es identificar las principales actividades logísticas que influyeron positivamente en las exportaciones de mango peruano con la sub partida número 0804502000 desde el Puerto de Paita hacia Estados Unidos durante los años 2012 y 2017. Se considera este periodo debido a que este puerto fue concesionado en el año 2009 a Terminales Portuarios Euroandinos, pero comenzó sus actividades en el año 2011. Durante los años 2012 y 2015 se observó que las exportaciones de mangos han tenido una tendencia positiva; sin embargo, en el año 2016 se aprecia una disminución. Cabe destacar que el Perú ocupa el sexto puesto en exportación de mango a nivel mundial, encontrándose por debajo de Brasil dentro de los países de Sudamérica. El Puerto de Paita es el principal punto de salida del mango al mercado internacional, siendo el primer país de destino Países Bajos, pero en este estudio se considerará al segundo país de destino, Estados Unidos por ser una potencia mundial y tener una gran extensión geográfica y poblacional, el cual está en crecimiento. Para analizar las principales actividades logísticas en este periodo se ha realizado una investigación cuantitativa, utilizando la herramienta de la encuesta con el instrumento cuestionario a 31 ejecutivos expertos en logística y comercio exterior de un total de 26 empresas exportadoras de mango desde el Puerto de Paita. Cabe resaltar que estas empresas representan el 80% de las exportaciones en el periodo analizado. Para hacer este análisis se ha utilizado el programa estadístico SPSS, con el fin de evaluar las hipótesis planteadas. De esta manera, se encontró que la mejora en las actividades logísticas: infraestructura, transporte y almacenaje desde la Concesión del Puerto ha influido positivamente en la exportación del mango durante el periodo analizado. Pero es necesario realizar algunas mejoras dentro de dicho puerto para que el valor exportado siga yendo en aumento en los siguientes años. / The objective of this research work is to identify the main logistics activities that have positively influenced in the export of Peruvian mango from the Port of Paita to the United States during the years 2012 to 2017. This period is considered due to the fact that this port was concessioned in 2009 to Port Terminals Euroandinos, but started its activities in 2011. During the years 2012 to 2015 it is observed that mango exports have had a positive trend; however, in 2016 there is a decrease. It should be noted that Peru occupies the sixth position in mango exports worldwide, being below Brazil with respect to the countries of South America. The Port of Paita is the main point of departure of the mango to the international market, being the first destination country The Netherlands, but in this study is considered the second country of destination the United States for being a world power and having a large geographical area and population, which is growing. To analyze the main logistic actions in this period, a quantitative investigation was carried out on 31 experts in logistics and foreign trade from a total of 26 mango exporting companies from the Port of Paita, using the survey tool with the questionnaire instrument. And with the statistical program SPSS, the factorial and discriminant analysis is obtained to determine the hypotheses proposed. In this way, it was found that the improvement in logistics actions: infrastructure, transport and storage by the Port Concession has positively influenced mango exports during the period analyzed. But it is necessary to make some improvements within this port so that the exported value continues to increase in the following years. / Tesis

Logistic regression is a widely used statistical method in data analysis and machine learning. When the capacity of data is large, it is time-consuming and even infeasible to perform big data machine learning using the traditional approach. Therefore, it is crucial to come up with an efficient way to evaluate feature combinations and update learning models. With the approach proposed by Yang, Wang, Xu, and Zhang (2018) a system can be represented using small enough matrices, which can be hosted in memory. These working sufficient statistics matrices can be applied in updating models in logistic regression. This study applies the working sufficient statistics approach in logistic regression machine learning to examine how this new method improves the performance. This study investigated the difference between the performance of this new working sufficient statistics approach and performance of the traditional approach on Spark\rq s machine learning package. The experiments showed that the working sufficient statistics method could improve the performance of training the logistic regression models when the input size was large.

This project analyzed the giving data of Worcester Polytechnic Institute's alumni and other constituents (parents, friends, neighbors, etc.) from fiscal year 1983 to 2007 using a two-stage modeling approach. Logistic regression analysis was conducted in the first stage to predict the likelihood of giving for each constituent, followed by linear regression method in the second stage which was used to predict the amount of contribution to be expected from each contributor. Box-Cox transformation was performed in the linear regression phase to ensure the assumption underlying the model holds. Due to the nature of the data, multiple imputation was performed on the missing information to validate generalization of the models to a broader population. Concepts from the field of direct and database marketing, like "score" and "lift", were also introduced in this report.

A inclusão da eletroencefalografia nos protocolos de pesquisa diagnóstica para DA é plenamente justificada por sua larga disponibilidade, baixo custo, alta sensibilidade, o que possibilita a realização de exames seriados e o acompanhamento da evolução do estudo neurológico. Objetivo: Determinar um índice de corte, para utilizaçào na prática clínica, no auxilio diagnóstico da doença de Alzheimer. Metodologia: Avaliamos dois grupos de indivíduos compostos por 57 voluntários normais e idade superior a 50 anos comparados a 50 indivíduos com DA provável. Realizamos registros de EEG em vigília, olhos fechados e repouso por 30 minutos e computamos as potências espectrais das bandas de frequência alfa e teta, para todos os eletrodos, e calculamos a razão alfa/teta. Realizamos a regressão logística das variáveis razão alfa/teta da potência média do eletrodo C3 e do eletrodo O1e calculamos uma fórmula para o auxílio no diagnóstico da DA com um acerto cuja, sensibilidade para DA de 76, 4 % e especificidadede 84,6 % e a área sob a curva ROC 0.92. Conclusão: A regressão logística da razão alfa/teta do Espectro da potência média do EEG é um bom marcador para discriminar pacientes com doença de Alzheimer de controles normais / The inclusion of electroencephalography in diagnostic research protocols for AD is fully justified given EEG\'s wide availability, low cost and high sensitivity, allowing serial exams and neurological evolution follow-ups. Objective: To determine a screening index for use in routine clinical practice to aid the diagnosis of Alzheimer\'s disease. Methodology: Two groups of individuals older than 50 years, comprising a control group of 57 normal volunteers and a study group of 50 patients with probable AD, were compared. EEG recordings were performed of subjects in a wake state with eyes closed at rest for 30 mins. Spectral potentials of the alpha and theta bands were computed for all electrodes and the alpha/theta ratio calculated. Logistic regression of the variables alpha/theta of the mean potential of the C3 and O1 electrodes was carried out. A formula was calculated to aid the diagnosis of AD yielding 76.4 % sensitivity and 84.6 specificity for AD with an area under the ROC curve of 0.92. Conclusion: Logistic regression of the alpha/theta of the Spectrum of the mean potential of EEG represents a good marker for discriminating between AD patients and normal controls

Esta dissertação tem como objetivo principal estudar a estabilidade assintótica de Equações Diferenciais com Retardamento utilizando as técnicas desenvolvidas por Faria e Liz (2003). Para analisar a estabilidade assintótica, a abordagem utilizada neste trabalho é a de impor uma condição de dominância do termo sem retardo sobre a parte com retardo, possibilitando o estudo de soluções oscilatórias. Além disso, o estudo culminará em um teorema que garante essa estabilidade em uma Equação do tipo Lotka-Volterra, para a qual o método de Liapunov não se aplica. Para atingir o objetivo, estudou-se inicialmente a teoria geral de estabilidade de Equações Diferenciais Funcionais e a teoria de estabilidade para alguns tipos dessas equações / This paper\'s main objective is to study the asymptotic stability of Dierential Equations with Delay using the techniques developed by Faria and Liz (2003). To analyze the asymptotic stability, the approach used in this study is to impose a condition of dominance of the term without delay on the part delayed, allowing the study of oscillatory solutions. In addition, the study will culminate in a theorem ensures such stability in an equation Lotka-Volterra type, for which the Liapunov method does not apply. To achieve the objective, we studied initially the general theory of stability of Functional Dierential Equations and stability theory for some types of these equations

Yiu Tat-choi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 68-69). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Student Ratings of Instructors --- p.2 / Chapter 1.2 --- Research Plan and Difficulties Encountered in the Study --- p.4 / Chapter 2 --- Data and An Overall Picture of Study --- p.7 / Chapter 2.1 --- The Questionnaire and Data Collection Method --- p.7 / Chapter 2.2 --- Pilot Study --- p.8 / Chapter 2.3 --- Data Editing --- p.12 / Chapter 2.3.1 --- Clerical Error --- p.12 / Chapter 2.3.2 --- Strange Patterns --- p.13 / Chapter 2.4 --- Missing Items ´ؤ Item Nonresponse --- p.14 / Chapter 2.5 --- Missing Items - Unit Nonresponse --- p.16 / Chapter 2.6 --- Effective Class Size --- p.21 / Chapter 2.7 --- Imputation of Item Nonresponse Data --- p.23 / Chapter 2.8 --- Overall Picture of Study --- p.25 / Chapter 3 --- Data Analysis I: Logistic Regression --- p.28 / Chapter 3.1 --- Conditional Independence --- p.29 / Chapter 3.2 --- Partial Correlation --- p.30 / Chapter 3.3 --- Simultaneous p-value --- p.31 / Chapter 3.4 --- Logit Model --- p.32 / Chapter 3.5 --- Logit Model for Ordinal Variables --- p.35 / Chapter 3.6 --- Iteratively Reweighted Least Squares (IRLS) Algorithm --- p.36 / Chapter 3.7 --- Criteria for Assessing Model Fit --- p.38 / Chapter 3.7.1 --- Assessing the Fit of the Model --- p.39 / Chapter 3.7.2 --- Pearson Chi-Square and Deviance --- p.40 / Chapter 3.8 --- Interpretation of the Coefficients of The Weighted Logistic Re- gression Model --- p.42 / Chapter 3.8.1 --- Nominal Independent Variable --- p.42 / Chapter 3.8.2 --- Continuous Independent Variable --- p.45 / Chapter 4 --- Data Analysis II: Adjusted Instructor Score --- p.49 / Chapter 4.1 --- Removing Effects of Class Characteristics Factor and Adjust- ing the Score --- p.50 / Chapter 4.2 --- Adjusted Instructor Score (AIS) --- p.54 / Chapter 4.3 --- Estimate Standard Error of AIS by Bootstrap Method --- p.55 / Chapter 5 --- Conclusion --- p.58 / Chapter 5.1 --- Comparison Between the AIS and Average Score --- p.58 / Chapter 5.2 --- Discussion --- p.60 / Appendix A1: Course Evaluation Survey Form --- p.63 / Appendix A2: Course Evaluation Supplementary Form . --- p.64 / Appendix B: Descriptive Statistics for Response Rate --- p.65 / Appendix C: The Descriptions of Class Characteristics Dummy Variables --- p.67 / Bibliography --- p.68

This study compares the behavior of differential equations and difference equations of various orders in order to predict the state of the systems at a given time by using initial information about the system. We have demonstrated that differential equations are used in a continuous domain whereas difference equations are employed for discrete dynamical systems. Furthermore, the difference between the two models is amplified in logistic models which both are known to give explicit solutions. However, the discrete logistic model is especially superior in exhibiting a chaotic behavior of the system which the differential equation is incapable of dealing with. The conclusions drawn from the findings conform the similarities and the stark differences between these two models.