<p>This dissertation investigates whether dual credit students' academic performance in subsequent university courses is comparable to that of non-dual-credit students. The study uses data from a Midwest regional public university over a ten-year period and employs propensity score matching and proportional odds ordinal logistic regression to create balanced comparison groups and analyze the results. The findings indicate that students who completed the prerequisite course as dual credit have similar grades in subsequent university courses as those who completed the prerequisite course as a university student. The study also identifies significant predictors of academic performance in subsequent university courses, such as sex, historically underserved groups status, high school GPA, and course subject, regardless of dual credit status. However, first-generation status, SAT scores, and the time between courses are not statistically significant predictors. These results suggest that dual credit students are as prepared for subsequent university courses as non-dual-credit students. Nevertheless, academic outcomes differ based on certain factors, which should be considered when designing student success initiatives and allocating resources.</p>

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INTRODUÇÃO: Não existem estudos preditivos sobre fadiga em doentes com câncer colo-retal, embora fadiga seja descrita como freqüente na população oncológica. OBJETIVO: Identificar os fatores de risco e preditivos independentes de fadiga em doentes com câncer colo-retal. MÉTODO: Estudo preditivo que envolveu amostra não-probabilística de 157 pacientes adultos ambulatoriais com tumor primário de cólon ou reto (idade média 60±11,7 anos; 54% homens; média de anos de escolaridade 10,7±5,4 anos; estádio IV 44,8%), atendidos em quatro serviços de oncologia do município de São Paulo, Brasil (julho/2006 a julho/2007). Os pacientes preencheram a Ficha de Identificação, a Escala de Fadiga de Piper-Revisada (0-10; ponto de corte: >4; ?=0,94), o Inventário de Depressão de Beck (0-63; ponto de corte: >13; ?=0,83), a Escala de Karnofky (0%-100%; ponto de corte: <80), a Escala de Prejuízo do Sono (0-10; ponto de corte: >5) e a Escala de Dor (0-10; ponto de corte: >6). Os pontos de corte foram estabelecidos pela análise da curva ROC (Receiver Operating Characteristic), com exceção do ponto de corte de fadiga, que foi estabelecido após análise da distribuição dos escores em percentis e do critério proposto pela National Comprehensive Cancer Network. RESULTADOS: Fadiga foi referida por 26,8% dos doentes. Os fatores de risco para fadiga foram os seguintes: serviço de saúde público, dor, prejuízo do sono, depressão e capacidade funcional prejudicada (p<0,05). A análise de regressão logística identificou três fatores preditivos: depressão, capacidade funcional e prejuízo do sono. A depressão aumentou em 4 vezes a chance de ocorrer fadiga (OR: 4,2; IC95% 1,68-10,39), a capacidade funcional aumentou em 3 vezes (OR: 3,2; IC95% 1,37-7,51) e o prejuízo do sono também em 3 vezes (OR: 3,2; IC95% 1,30-8,09). Quando os três fatores preditivos estiveram presentes, a probabilidade de ocorrer fadiga foi de 80%, o que indicou boa capacidade de predição. Quando os três fatores preditivos estiveram ausentes, a probabilidade de ocorrer fadiga foi de 8%. A especificidade e sensibilidade do modelo foram de 81,9% e 58,6%, respectivamente, indicando baixa chance de falsos positivos e alta chance de falsos negativos. CONCLUSÕES: Depressão, capacidade funcional e prejuízo do sono foram preditores de fadiga. O estudo disponibiliza tabela de probabilidade de predição de fadiga e propõe que, por meio da avaliação da depressão, da capacidade funcional e do prejuízo do sono, é possível conhecer a probabilidade do paciente ter fadiga, o que é inédito nessa população e de grande utilidade na clínica / INTRODUCTION: There are no studies that identify the predictive factors of fatigue among colo-rectal cancer patients, although fatigue is described as a frequent problem in the oncology setting. AIM: Identify risk factors and independent predictors of fatigue in colo-rectal cancer patients. METHOD: Predictive study that involved non-probabilistic sample of 157 adult outpatients with primary colon or rectal (mean age 60±11.7 years; 54% male; educational level 10.7±5.4 years; cancer stage IV 44.8%), recruited from 4 oncology clinics in Sao Paulo, Brazil (July/2006 to July/2007). Patients filled out an Identification Profile, Piper Fatigue Scale-revised (0-10; cut-score: >4, ?=0,94), Beck Depression Inventory (0-63; cut-score: >13, ?=0,83), Karnofsky Scale (0%-100%; cut-score: <80%), Sleep disturbance scale (0-10; cut-score: >5), and Pain scale (0-10; cut-score: >6). The cut scores were established by ROC (Receiver Operating Characteristic) curves, except for fatigue cut-score, which was established after an analysis of the distribution of the scores in percentiles and of the criteria proposed by National Comprehensive Cancer Network. RESULTS: Fatigue was identified by 26.8% of the patients. The risk factors for fatigue were: public oncology service, pain, sleep disturbance, poor performance status, and depression (p<0.05). Logistic regression identified three predictors: depression, sleep disturbance, and performance status. Depression increased the chance for fatigue to occur by four times (OR: 4.2; 95%CI 1.68-10.39), performance status increased by three times (OR: 3.2; 95%CI 1.37-7.51), and sleep disturbance also increased the chance by three times (OR: 3.2; 95%CI 1.30-8.09). When the three factors were present in concomitance, the probability that patients had fatigue was 80%, which was considered a good predictive capacity. When none of the factors were present, the probability that patients had fatigue was 8%. The specificity and sensibility of this model were 81.9% and 58.6%, respectively, indicating that there is low chance of false positive and high chance of false negatives. CONCLUSIONS: Depression, performance status, and sleep disturbance were predictive factors of fatigue. The study presents a prediction table and proposes that by assessing depression, performance status and sleep disturbance, it is possible to know the probability that a patient will have fatigue. This finding is original and applicable in clinical practice

A toxocaríase é uma zoonose muito difundida em todo o mundo. Trata-se da infecção humana, em especial pelas larvas de Toxocara canis, um nematóide comum de cães. O objetivo do presente estudo foi levantar a soropositividade a anticorpos anti-Toxocara spp, identificar os fatores de risco em grupos de escolares da cidade de Fernandópolis/SP e avaliar a contaminação do solo por ovos desse e de outros geo-helmintos entre os anos de 2007 e 2008. Foi realizado um estudo transversal utilizando-se amostragem complexa e estratificada, por renda, para a avaliação da toxocaríase humana. O método diagnóstico empregado foi o teste de ELISA para detecção de anticorpos IgG anti-Toxocara spp. O estudo da contaminação do solo deu-se por meio da avaliação de amostras de solo de praças, parques públicos e escolas municipais e pela avaliação de amostras de fezes provenientes de 10 praças públicas. Foram avaliados 252 indivíduos em dois estratos, o primeiro representando baixa renda com 120 (47,6%) crianças e o segundo com 132 (52,4%) representando renda elevada. A frequência geral de positividade ao antígeno TES foi de 15,4% (39), sendo 28,3% (34) para o primeiro estrato contra 3,7% (5) do segundo (p<0,000). A exposição à geofagia (exposto OR ajustado 14,65 - IC95% = 2,14 a 89,25 e muito expostos OR ajustado 19,15 a IC95% = 2,96 a 123,94), o hábito de levar objetos à boca (exposto OR ajustado 9,31 - IC95% = 1,63 a 53,03 e muito expostos OR ajustado 42,29 a IC95% = 5,49 a 326,01) e a presença de mais de dois cães em domicílio (OR ajustado 21,25 = 1,7 a 264,87) foram variáveis associadas à positividade. O hábito de lavar as mãos antes das refeições (OR ajustado 0,01 - IC95% 0,00 a 0,05) representou importante fator de proteção. Foram avaliadas 225 amostras de solo, sendo 71% (160) provenientes de praças e parques públicos e 29% (65), de escolas municipais. Foi observado alto grau de contaminação de praças e parques públicos 28,4% (64), ao passo que nas escolas a positividade foi de 1,7% (6). Os parasitos encontrados com maior frequência foram de Toxocara spp 79,6% (47), Trichuris spp 13,5% (8) e ancilostomídeo 6,4% (4). Foram avaliadas ainda 400 amostras de fezes de cães, e observou-se uma positividade de 23,7% (95). Os parasitos observados com maior frequência nas amostras positivas foram ancilostomídeo símile 74,7% (71) e Toxocara canis, 53,6% (51). A positividade a anticorpos anti-Toxocara spp em indivíduos de 1 a 12 anos de idade, provenientes de cinco escolas do município de Fernandópolis/SP, foi relativamente baixa. Os principais fatores de risco/proteção dizem respeito às questões modificáveis como a geofagia, o hábito de levar objetos à boca, a existência de mais de dois cães em domicílio e o hábito de lavar as mãos antes das refeições. Os solos de praças e parques públicos de Fernandópolis/SP e amostras de fezes recolhidas em ambiente estavam altamente contaminados com geo-helmintos zoonóticos e representam fonte de infecção relevante para a população / Toxocariasis is a zoonosis of worldwide occurrence. It is defined as the human infection by larvae of nematodes, especially Toxocara canis, common intestinal parasite of dogs. The aim of this study was to estimate the frequency of anti-Toxocara spp antibodies, identify risk factors in groups of school children from the city of Fernandópolis/SP and evaluate soil contamination by eggs of this and other geohelminths between 2007 and 2008. It was conducted a cross-sectional study using complex sampling for the assessment of human toxocariasis. The diagnostic method used was the ELISA test for detection of IgG anti-Toxocara spp antibodies. The study of soil contamination was done through evaluation of soil samples from public places, sand boxes of municipal schools and evaluation of dogs stool samples from 10 public places. Two hundred and fifty two children were evaluated in two strata, the first with 120 children (47.6%) from low income families and the second with 132 (52.4%) from high income ones. The overall frequency of antibodies anti-Toxocara spp was 15.4% (39), being 28.3% (34) for the first stratum compared with 3.7% (5) of the second (p <0.000). The exposure to geophagy (exposed: adjusted OR 14.65 - CI 95% = 2.14 to 89.25; very exposed: adjusted OR 19.15 - CI 95%= 2.96 to 123.94), the habit of rising objects up to the mouth (exposed: adjusted OR 9.31 1.63 to 53.03; very exposed: adjusted OR 42.29 - CI 95%= 5.49 to 326.01) and the presence of more than two dogs at home (adjusted OR 21.25 - 1.7 to 264.87) were variables associated with positivity. The habit of washing hands before meals (adjusted OR 0.01 - CI 95% = 0.00 to 0.05) represented an important protective factor. Were evaluated 225 samples of soil: 71% (160) from public places and 29% (65) of municipal schools. It was observed a high contamination of public places with 28.4% (64) being positive, while in school positivity was 1.7% (6). The most frequent parasites eggs found were Toxocara spp 79.6% (47), Trichuris spp 13.5% (8) and Ancylostomatidae 6.4% (4). They were also evaluated 400 fecal samples of dogs and observed a positivity of 23.7% (95). The most frequent parasites observed in positive samples were Ancylostoma simile 74.7% (71) and Toxocara canis 53.6% (51). The anti-Toxocara spp antibodies positivity in school children from Fernandópolis/SP was relatively low. The main factors of risk/protection concern to modifiable issues like geophagy, the habit of rising objects up to the mouth, the existence of more than two dogs at home and the habit of washing hands before meals. The soil of public places of Fernandópolis/SP and feces samples collected from the environment were highly contaminated with zoonotic helminths and represent important source of infection for the population

INTRODUÇÃO: Não existem estudos preditivos sobre fadiga em doentes com câncer colo-retal, embora fadiga seja descrita como freqüente na população oncológica. OBJETIVO: Identificar os fatores de risco e preditivos independentes de fadiga em doentes com câncer colo-retal. MÉTODO: Estudo preditivo que envolveu amostra não-probabilística de 157 pacientes adultos ambulatoriais com tumor primário de cólon ou reto (idade média 60±11,7 anos; 54% homens; média de anos de escolaridade 10,7±5,4 anos; estádio IV 44,8%), atendidos em quatro serviços de oncologia do município de São Paulo, Brasil (julho/2006 a julho/2007). Os pacientes preencheram a Ficha de Identificação, a Escala de Fadiga de Piper-Revisada (0-10; ponto de corte: >4; ?=0,94), o Inventário de Depressão de Beck (0-63; ponto de corte: >13; ?=0,83), a Escala de Karnofky (0%-100%; ponto de corte: <80), a Escala de Prejuízo do Sono (0-10; ponto de corte: >5) e a Escala de Dor (0-10; ponto de corte: >6). Os pontos de corte foram estabelecidos pela análise da curva ROC (Receiver Operating Characteristic), com exceção do ponto de corte de fadiga, que foi estabelecido após análise da distribuição dos escores em percentis e do critério proposto pela National Comprehensive Cancer Network. RESULTADOS: Fadiga foi referida por 26,8% dos doentes. Os fatores de risco para fadiga foram os seguintes: serviço de saúde público, dor, prejuízo do sono, depressão e capacidade funcional prejudicada (p<0,05). A análise de regressão logística identificou três fatores preditivos: depressão, capacidade funcional e prejuízo do sono. A depressão aumentou em 4 vezes a chance de ocorrer fadiga (OR: 4,2; IC95% 1,68-10,39), a capacidade funcional aumentou em 3 vezes (OR: 3,2; IC95% 1,37-7,51) e o prejuízo do sono também em 3 vezes (OR: 3,2; IC95% 1,30-8,09). Quando os três fatores preditivos estiveram presentes, a probabilidade de ocorrer fadiga foi de 80%, o que indicou boa capacidade de predição. Quando os três fatores preditivos estiveram ausentes, a probabilidade de ocorrer fadiga foi de 8%. A especificidade e sensibilidade do modelo foram de 81,9% e 58,6%, respectivamente, indicando baixa chance de falsos positivos e alta chance de falsos negativos. CONCLUSÕES: Depressão, capacidade funcional e prejuízo do sono foram preditores de fadiga. O estudo disponibiliza tabela de probabilidade de predição de fadiga e propõe que, por meio da avaliação da depressão, da capacidade funcional e do prejuízo do sono, é possível conhecer a probabilidade do paciente ter fadiga, o que é inédito nessa população e de grande utilidade na clínica / INTRODUCTION: There are no studies that identify the predictive factors of fatigue among colo-rectal cancer patients, although fatigue is described as a frequent problem in the oncology setting. AIM: Identify risk factors and independent predictors of fatigue in colo-rectal cancer patients. METHOD: Predictive study that involved non-probabilistic sample of 157 adult outpatients with primary colon or rectal (mean age 60±11.7 years; 54% male; educational level 10.7±5.4 years; cancer stage IV 44.8%), recruited from 4 oncology clinics in Sao Paulo, Brazil (July/2006 to July/2007). Patients filled out an Identification Profile, Piper Fatigue Scale-revised (0-10; cut-score: >4, ?=0,94), Beck Depression Inventory (0-63; cut-score: >13, ?=0,83), Karnofsky Scale (0%-100%; cut-score: <80%), Sleep disturbance scale (0-10; cut-score: >5), and Pain scale (0-10; cut-score: >6). The cut scores were established by ROC (Receiver Operating Characteristic) curves, except for fatigue cut-score, which was established after an analysis of the distribution of the scores in percentiles and of the criteria proposed by National Comprehensive Cancer Network. RESULTS: Fatigue was identified by 26.8% of the patients. The risk factors for fatigue were: public oncology service, pain, sleep disturbance, poor performance status, and depression (p<0.05). Logistic regression identified three predictors: depression, sleep disturbance, and performance status. Depression increased the chance for fatigue to occur by four times (OR: 4.2; 95%CI 1.68-10.39), performance status increased by three times (OR: 3.2; 95%CI 1.37-7.51), and sleep disturbance also increased the chance by three times (OR: 3.2; 95%CI 1.30-8.09). When the three factors were present in concomitance, the probability that patients had fatigue was 80%, which was considered a good predictive capacity. When none of the factors were present, the probability that patients had fatigue was 8%. The specificity and sensibility of this model were 81.9% and 58.6%, respectively, indicating that there is low chance of false positive and high chance of false negatives. CONCLUSIONS: Depression, performance status, and sleep disturbance were predictive factors of fatigue. The study presents a prediction table and proposes that by assessing depression, performance status and sleep disturbance, it is possible to know the probability that a patient will have fatigue. This finding is original and applicable in clinical practice

We consider a longitudinal system in which transitions between the states are governed by a discrete time finite state space stochastic process X. Our aim, using aggregated sample survey data of the form typically collected by official statistical agencies, is to undertake model based inference for the underlying process X. We will develop inferential techniques for continuing sample surveys of two distinct types. First, longitudinal surveys in which the same individuals are sampled in each cycle of the survey. Second, cross-sectional surveys which sample the same population in successive cycles but with no attempt to track particular individuals from one cycle to the next. Some of the basic results have appeared in Davis et al (2001) and Davis et al (2002).¶ Longitudinal surveys provide data in the form of transition frequencies between the states of X. In Chapter Two we develop a method for modelling and estimating the one-step transition probabilities in the case where X is a non-homogeneous Markov chain and transition frequencies are observed at unit time intervals. However, due to their expense, longitudinal surveys are typically conducted at widely, and sometimes irregularly, spaced time points. That is, the observable frequencies pertain to multi-step transitions. Continuing to assume the Markov property for X, in Chapter Three, we show that these multi-step transition frequencies can be stochastically interpolated to provide accurate estimates of the one-step transition probabilities of the underlying process. These estimates for a unit time increment can be used to calculate estimates of expected future occupation time, conditional on an individual’s state at initial point of observation, in the different states of X.¶ For reasons of cost, most statistical collections run by official agencies are cross-sectional sample surveys. The data observed from an on-going survey of this type are marginal frequencies in the states of X at a sequence of time points. In Chapter Four we develop a model based technique for estimating the marginal probabilities of X using data of this form. Note that, in contrast to the longitudinal case, the Markov assumption does not simplify inference based on marginal frequencies. The marginal probability estimates enable estimation of future occupation times (in each of the states of X) for an individual of unspecified initial state. However, in the applications of the technique that we discuss (see Sections 4.4 and 4.5) the estimated occupation times will be conditional on both gender and initial age of individuals.¶ The longitudinal data envisaged in Chapter Two is that obtained from the surveillance of the same sample in each cycle of an on-going survey. In practice, to preserve data quality it is necessary to control respondent burden using sample rotation. This is usually achieved using a mechanism known as rotation group sampling. In Chapter Five we consider the particular form of rotation group sampling used by the Australian Bureau of Statistics in their Monthly Labour Force Survey (from which official estimates of labour force participation rates are produced). We show that our approach to estimating the one-step transition probabilities of X from transition frequencies observed at incremental time intervals, developed in Chapter Two, can be modified to deal with data collected under this sample rotation scheme. Furthermore, we show that valid inference is possible even when the Markov property does not hold for the underlying process.

<p>This study extends the existing literature on how social networks enhance the performance and sustainability of small enterprises. More specifically, the study isolates and investigates the mechanisms through which social capital helps with the growth and survival of MSMEs. The evidence presented in this study strongly suggests that an indigenous social network widely practiced in Ethiopia, the &ldquo / iqqub&rdquo / , contributes significantly to the start-up, survival and development of urban MSMEs.</p>

Chen(2010)提出如何用勝率函數來判斷給定的連續條件分配是否相容，以及 相容時如何求對應的聯合分配。本研究提出，在二維有限的情形下，如何用勝率 矩陣來判斷給定的條件機率矩陣是否相容，以及相容時如何求對應的聯合機率矩 陣。又給定的條件機率矩陣不相容時，我們介紹了四種修改勝率矩陣的方法，同 時在使用幾何平均法調整勝率矩陣的過程中，也發現選取最佳參考點以獲得最佳 近似聯合機率矩陣之方法，並且給予理論證明。最後以模擬的方式發現，在修改 勝率矩陣的四種方法中，以幾何平均法所得到的近似聯合機率矩陣，其條件機率 矩陣最常接近所給定的條件機率矩陣。 / Chen (2010) provides the representations of odds ratio function to examine the compatibility of conditional probability density functions and gives the corresponding joint probability density functions if they are compatible. In this research, we provide the representations of odds ratio matrix to examine the compatibility of two discrete conditional probability matrices and give the corresponding joint probability matrix if they are compatible. For incompatible situations, we offer four methods to revise odds ratio matrices to find near joint probability matrices so that their conditional probability matrices are not far from the two given ones. That is, we provide four methods so that the sums of error squares are small. For each method, the sum of error squares may depend on the same reference point of two odds ratio matrices. We first discover by example that only the geometric method out of these four methods has a pattern to get the best reference point so that the sum of error squares is smallest. We then prove this finding in general. In addition, through simulation results, the geometric method would provide the smallest sum of error squares most often among these four methods. Hence, we suggest using geometric method. Its strategy to find the best reference point is also given.

In the dissertation, we study the statistical evaluation of treatment comparisons by evaluating the relative comparison of survival experiences between two treatment groups. We construct confidence interval and simultaneous confidence bands for the ratio and odds ratio of two survival functions through both parametric and nonparametric approaches.We first construct empirical likelihood confidence interval and simultaneous confidence bands for the odds ratio of two survival functions to address small sample efficacy and sufficiency. The empirical log-likelihood ratio is developed, and the corresponding asymptotic distribution is derived. Simulation studies show that the proposed empirical likelihood band has outperformed the normal approximation band in small sample size cases in the sense that it yields closer coverage probabilities to chosen nominal levels.Furthermore, in order to incorporate prognostic factors for the adjustment of survival functions in the comparison, we construct simultaneous confidence bands for the ratio and odds ratio of survival functions based on both the Cox model and the additive risk model. We develop simultaneous confidence bands by approximating the limiting distribution of cumulative hazard functions by zero-mean Gaussian processes whose distributions can be generated through Monte Carlo simulations. Simulation studies are conducted to evaluate the performance for proposed models. Real applications on published clinical trial data sets are also studied for further illustration purposes.In the end, the population attributable fraction function is studied to measure the impact of risk factors on disease incidence in the population. We develop semiparametric estimation of attributable fraction functions for cohort studies with potentially censored event time under the additive risk model.