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Computer-aided National Early Warning Score to predict the risk of sepsis following emergency medical admission to hospital: a model development and external validation studyFaisal, Muhammad, Richardson, D., Scally, Andy J., Howes, R., Beatson, K., Speed, K., Mohammad, Mohammad A. 20 March 2019 (has links)
Yes / In English hospitals, the patient’s vital signs are monitored and summarised into a National Early Warning Score (NEWS). NEWS is more accurate than the quick sepsis related organ failure assessment (qSOFA) score at identifying patients with sepsis. We investigate the extent to which the accuracy of the NEWS is enhanced by developing computer-aided NEWS (cNEWS) models. We compared three cNEWS models (M0=NEWS alone; M1=M0 + age + sex; M2=M1 + subcomponents of NEWS + diastolic blood pressure) to predict the risk of sepsis.
Methods: All adult emergency medical admissions discharged over 24-months from two acute hospitals (YH–York Hospital for model development; NH–Northern Lincolnshire and Goole Hospital for external model validation). We used a validated Canadian method for defining sepsis from administrative hospital data.
Findings: The prevalence of sepsis was lower in YH (4.5%=1596/35807) than NH (8.5%=2983/35161). The c-statistic increased across models (YH: M0: 0.705, M1:0.763, M2:0.777; NH:M0: 0.708, M1:0.777, M2:0.791). At NEWS 5+, sensitivity increased (YH: 47.24% vs 50.56% vs 52.69%; NH: 37.91% vs 43.35% vs 48.07%)., the positive likelihood ratio increased (YH: 2.77 vs 2.99 vs 3.06; NH: 3.18 vs 3.32 vs 3.45) and the positive predictive value increased (YH: 11.44% vs 12.24% vs 12.49%; NH: 22.75% vs 23.55% vs 24.21%).
Interpretation: From the three cNEWS models, Model M2 is the most accurate. Since it places no additional data collection burden on clinicians and can be automated, it may now be carefully introduced and evaluated in hospitals with sufficient informatics infrastructure. / The Health Foundation, National Institute for Health Research (NIHR) Yorkshire and Humberside Patient Safety Translational Research Centre / Research Development Fund Publication Prize Award winner, April 2019.
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The impact of misspecification of nuisance parameters on test for homogeneity in zero-inflated Poisson model: a simulation studyGao, Siyu January 1900 (has links)
Master of Science / Department of Statistics / Wei-Wen Hsu / The zero-inflated Poisson (ZIP) model consists of a Poisson model and a degenerate distribution at zero. Under this model, zero counts are generated from two sources, representing a heterogeneity in the population. In practice, it is often interested to evaluate this heterogeneity is consistent with the observed data or not. Most of the existing methodologies to examine this heterogeneity are often assuming that the Poisson mean is a function of nuisance parameters which are simply the coefficients associated with covariates. However, these nuisance parameters can be misspecified when performing these methodologies. As a result, the validity and the power of the test may be affected. Such impact of misspecification has not been discussed in the literature. This report primarily focuses on investigating the impact of misspecification on the performance of score test for homogeneity in ZIP models. Through an intensive simulation study, we find that: 1) under misspecification, the limiting distribution of the score test statistic under the null no longer follows a chi-squared distribution. A parametric bootstrap methodology is suggested to use to find the true null limiting distribution of the score test statistic; 2) the power of the test decreases as the number of covariates in the Poisson mean increases. The test with a constant Poisson mean has the highest power, even compared to the test with a well-specified mean. At last, simulation results are applied to the Wuhan Inpatient Care Insurance data which contain excess zeros.
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Undersöka handläggning av normal förlossningen med hjälp av Bologna ScoreSandgren, Annika January 2016 (has links)
I Sverige har barnmorskan ett eget ansvar att handlägga den normala förlossningen samt värna om det normala barnafödandet. Enligt riktlinjer både internationellt och nationellt är det övergripande målet med förlossningsvården att mamma och barn skall må bra och att förlossningen handläggs med så få interventioner som möjligt. Flera studier visar att interventioner under förlossning ökar och att förlossningsvården bara till viss del utgår från den evidens som finns kring normal förlossning. Syftet med studien var att undersöka handläggning av normal förlossning med hjälp av instrumentet Bologna Score. En prospektiv tvärsnittsstudie med kvantitativ ansats har använts. Nitton barnmorskestudenter på ett lärosäte i Västsverige fick efter varje förlossning de medverkat vid fylla i ett frågeformulär med instrumentet Bologna Score som skattar hur normal förlossning handläggs. Frågeformuläret är testat och validerat och har använts i tidigare studier. Resultatet visar att 20,3 % av alla förlossningar i föreliggande studie fick 5 poäng på Bologna Score, vilket indikerar att dessa förlossningen handlagts med aktuell evidens. Medelvärdet på Bologna Score var 3,73 poäng. Trots det låga resultatet på Bologna Score så bedömdes 73,8 % av förlossningarna som normala av barnmorskestudenterna. Resultatet indikerar att handläggningen av förlossningarna inte till fullo utgår från den evidens som finns. Vidare framkom att det är möjligt att Bologna Score inte är tillräckligt specifikt för att särskilja de förlossningar som avses att analyseras. Resultatet visar också på signifikanta skillnader mellan olika förlossningsklinikers handläggning av normal förlossning.
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The effects of English-medium instruction on language proficiency of students enrolled in higher education in the UAERogier, Dawn January 2012 (has links)
This research seeks to discover what happens to students’ English language skills while studying in English-medium classes in UAE universities, and to look at how this compares with what instructors and students think happens to students’ English proficiency during the four years of study. This is explored through a retrospective panel study using a test/retest method to investigate score gains on the IELTS exam after four years of undergraduate study. Student and teacher beliefs about how English-medium instruction (EMI) affects language proficiency, the need for language support after admission, and the selection and delivery of course materials are discussed in conjunction with the research findings, leading to recommendations for institutions whose primary goal in using EMI is to increase proficiency. This research continues the exploratory research of Elder and O’Loughlin (2003) and O’Loughlin and Arkoudis (2009) regarding score gains in IELTS after a course of study, but this study is situated in a society where the language of instruction is not the language of communication for the students outside the university and at home. The research findings indicate that there is a statistically significant score gain in all four of the English-language skill areas that are tested by the IELTS exam after four years of EMI for the participants in this study. The most gain occurred in the area of speaking, followed by reading, writing and then listening. Results from questionnaires and interviews indicate that students and teachers have different perceptions regarding language ability and the problems associated with the use of English for instruction. Students generally do not feel that studying in English causes problems for them, and they rate their ability in listening, reading, writing and speaking as good to excellent. On the other hand, teachers do not feel their students’ language ability meets expectations for students studying in an English-medium environment and think that their students are especially weak in the areas of writing and listening. Teachers feel that they must make adaptations to course content and assessment criteria due to students’ language ability. The research indicates that institutions whose goal it is to increase language proficiency through EMI need to have clear instructional goals in place for language development along with support systems for teachers and learners throughout the entire educational experience and not just in pre-academic support programs.
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The effects of score study on novices’ conducting and rehearsal behaviorsSilvey, Brian Ashley 15 February 2010 (has links)
This study investigated the effects of score study on novice conductors’ nonverbal and verbal conducting behaviors. Presented with a brief musical excerpt of which they had no prior knowledge, undergraduate conducting students (N = 11) conducted and rehearsed a live brass quartet. After an initial conducting session, participants in the experimental group (n = 6) received two individual 30-minute score study tutorials, while the control group (n = 5) received no assistance. All participants returned one week after the first conducting session to conduct and rehearse the ensemble for a second time. Brass quartet members and three experienced conductors, all whom were blind to the experimental condition, evaluated participants’ conducting in terms of eye contact, facial expression, effective gesture, ability to lead toward a musically accurate performance, knowledge of the score, and pacing. Significant differences were found between the score study and control conditions. The brass quartet members’ ratings for eye contact and knowledge of the score were higher for the participants who studied the score. I found no significant differences between conditions in the ratings given by experienced conductors. At the conclusion of the second rehearsal, brass quartet members accurately identified five of the six conductors who had received score study assistance and four of the five conductors who had not. Experienced conductors were asked to identify the order of the two videos of each conductor. They accurately identified the order of five of the six score study conductors’ videos. Identifications of participants’ videos in the control group were mostly inaccurate and reflected much disagreement among the experienced conductors. In reviews of the participants’ written and verbal responses about their experience and the comments provided by brass quartet members and experienced conductors, I noted three characteristics that distinguished those who engaged in score study from those who had not: (1) more meaningful, instrument-specific eye contact; (2) greater confidence and comfort; and (3) more effective gestures and other nonverbal behaviors in rehearsal, all of which seemed to result from a more clearly defined interpretation of the music. / text
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ALABAMA SUMMER: SUITE FOR ORCHESTRA WITH STRUCTURAL AND HARMONIC ANALYSISMcKee, David Frank 01 January 2008 (has links)
An original composition in three movements for large orchestra. Following the score is a detailed analysis of the work, consisting of an introduction, three sections of analysis devoted to each of the three movements of the composition, and a short conclusion summarizing the analysis.
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AN INVESTIGATION INTO LONG-RUN ABNORMAL RETURNS USING PROPENSITY SCORE MATCHINGAcharya, Sunayan 01 January 2012 (has links)
This is a study in two parts. In part-1, I identify several methods of estimating long-run abnormal returns prevalent in the finance literature and present an alternative using propensity score matching. I first demonstrate the concept with a simple simulation using generated data. I then employ historical returns from CRSP and randomly select events from the dataset using various alternating criteria. I test the efficacy of different methods in terms of type-I and type-II errors in detecting abnormal returns over 12- 36- and 60- month periods. I use various forms of propensity score matching: 1--5 Nearest Neighbors in Caliper using distance defined alternatively by Propensity Scores and the Mahalanobis Metric, and Caliper Matching. I show that overall, Propensity Score Matching with two nearest neighbors provides much better performance than traditional methods, especially when the occurence of events is dictated by the presence of certain firm characteristics.
In part-2, I demonstrate an application of Propensity Score Matching in the context of open-market share repurchase announcements. I show that traditional methods are ill-suited for the calculation of long-run abnormal returns following such events. Consequently, I am able to improve upon such methods on two fronts. First, I improve upon traditional matching methods by providing better matches on multiple dimensions and by being able to retain a larger sample of firms from the dataset. Second, I am able to eliminate much of the bias inherent in the Fama-French type methods for this particular application. I show this using simulations on samples based on firms that resemble a typical repurchasing firm. As a result, I obtain a statistically significant 1-, 3-, and 5- year abnormal return of about 2%, 5%, and 10% respectively, which is much lower than what prior literature has shown using traditional methods. Further investigation revealed that much of these returns are unique to small and unprofitable firms.
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MODÈLE À RISQUES COMPÉTITIFS ET ANALYSE DE PROPENSION APPLIQUÉS À L'ATTEINTE RÉNALE AIGUË EN RÉANIMATIONClec'H, Christophe 09 December 2010 (has links) (PDF)
L'atteinte rénale aiguë (ARA) est une pathologie fréquente en réanimation. La littérature actuelle sur le sujet est riche mais globalement hétérogène et confuse. Ainsi, plusieurs questions clés restent à ce jour sans réponse claire. Le but de cette thèse est d'apporter des éléments nouveaux dans le domaine dans un souci de rigueur et d'originalité méthodologiques. La première partie est consacrée à l'appréciation précise de l'impact pronostique de l'ARA par le modèle à risques compétitifs de Fine et Gray. La deuxième est dédiée à l'évaluation de l'efficacité de l'épuration extra-rénale (EER) par la technique du score de propension. La troisième, enfin, s'intéresse à l'ARA induite par les produits de contraste iodés, cas particulier potentiellement grave mais étonnamment peu étudié jusqu'alors en réanimation. Les résultats soulignent le pronostic sombre associé à la survenue d'une ARA, l'efficacité incertaine de l'EER et la nécessité urgente d'uniformisation des pratiques en termes de diagnostic et de thérapeutique.
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Evaluating the Use of Ridge Regression and Principal Components in Propensity Score Estimators under MulticollinearityGripencrantz, Sarah January 2014 (has links)
Multicollinearity can be present in the propensity score model when estimating average treatment effects (ATEs). In this thesis, logistic ridge regression (LRR) and principal components logistic regression (PCLR) are evaluated as an alternative to ML estimation of the propensity score model. ATE estimators based on weighting (IPW), matching and stratification are assessed in a Monte Carlo simulation study to evaluate LRR and PCLR. Further, an empirical example of using LRR and PCLR on real data under multicollinearity is provided. Results from the simulation study reveal that under multicollinearity and in small samples, the use of LRR reduces bias in the matching estimator, compared to ML. In large samples PCLR yields lowest bias, and typically was found to have the lowest MSE in all estimators. PCLR matched ML in bias under IPW estimation and in some cases had lower bias. The stratification estimator was heavily biased compared to matching and IPW but both bias and MSE improved as PCLR was applied, and for some cases under LRR. The specification with PCLR in the empirical example was usually most sensitive as a strongly correlated covariate was included in the propensity score model.
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The performance of insolvency prediction and credit risk models in the UK : a comparative study, development and wider applicationWood, Anthony Paul January 2012 (has links)
Contingent claims models have recently been applied to the field of corporate insolvency prediction in an attempt to provide the art with a theoretical methodology that has been lacking in the past. Limited studies have been carried out in order to empirically compare the performance of these “market” models with that of their accounting number-based counterparts. This thesis contributes to the literature in several ways: The thesis traces the evolution of the art of corporate insolvency prediction from its inception through to the present day, combining key developments and methodologies into a single document of reference. I use receiver operating characteristic curves and tests of economic value to assess the efficacy of sixteen models, carefully selected to represent key moments in the evolution of the art, and tested upon, for the first time, post-IFRS UK data. The variability of model efficacy is also measured for the first time, using Monte Carlo simulation upon 10,000 randomly generated training and validation samples from a dataset consisting of over 12,000 firmyear observations. The results provide insights into the distribution of model accuracy as a result of sample selection, which is something which has not appeared in the literature prior to this study. I find overall that the efficacy of the models is generally less than that reported in the prior literature; but that the theoretically driven, market-based models outperform models which use accounting numbers; the latter showing a relatively larger efficacy distribution. Furthermore, I obtain the counter-intuitive finding that predictions based on a single ratio can be as efficient as those which are based on models which are far more complicated – in terms of variable variety and mathematical construction. Finally, I develop and test a naïve version of the down-and-out-call barrier option model for insolvency prediction and find that, despite its simple formulation, it performs favourably compared alongside other market-based models.
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