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Early Warning System of Students Failing a Course : A Binary Classification Modelling Approach at Upper Secondary School Level / lFörebyggande Varningssystem av elever med icke godkänt betyg : Genom applicering av binär klassificeringsmodell inom gymnasieskolanKarlsson, Niklas, Lundell, Albin January 2022 (has links)
Only 70% of the Swedish students graduate from upper secondary school within the given time frame. Earlier research has shown that unfinished degrees disadvantage the individual student, policy makers and society. A first step for preventing dropouts is to indicate students about to fail courses. Thus the purpose is to identify tendencies whether a student will pass or not pass a course. In addition, the thesis accounts for the development of an Early Warning System to be applied to signal which students need additional support from a professional teacher. The used algorithm Random Forest functioned as a binary classification model of a failed grade against a passing grade. Data in the study are in samples of approximately 700 students from an upper secondary school within the Stockholm municipality. The chosen method originates from a Design Science Research Methodology that allows the stakeholders to be involved in the process. The results showed that the most dominant indicators for classifying correct were Absence, Previous grades and Mathematics diagnosis. Furthermore, were variables from the Learning Management System predominant indicators when the system also was utilised by teachers. The prediction accuracy of the algorithm indicates a positive tendency for classifying correctly. On the other hand, the small number of data points imply doubt if an Early Warning System can be applied in its current state. Thus, one conclusion is in further studies, it is necessary to increase the number of data points. Suggestions to address the problem are mentioned in the Discussion. Moreover, the results are analysed together with a review of the potential Early Warning Systemfrom a didactic perspective. Furthermore, the ethical aspects of the thesis are discussed thoroughly. / Endast 70% av svenska gymnasieelever tar examen inom den givna tidsramen. Tidigare forskning har visat att en oavslutad gymnasieutbildning missgynnar både eleven och samhället i stort. Ett första steg mot att förebygga att elever avviker från gymnasiet är att indikera vilka studenter som är på väg mot ett underkänt betyg i kurser. Därmed är syftet med rapporten att identifiera vilka trender som bäst indikerar att en elev kommer klara en kurs eller inte. Dessutom redogör rapporten för utvecklandet av ett förebyggande varningssystem som kan appliceras för att signalera vilka studenter som behöver ytterligare stöd från läraren och skolan. Algoritmen som användes var Random Forest och fungerar som en binär klassificeringsmodell av ett underkänt betyg mot ett godkänt. Den data som använts i studien är datapunkter för ungefär 700 elever från en gymnasieskola i Stockholmsområdet. Den valda metoden utgår från en Design Science Researchmetodik vilket möjliggör för intressenter att vara involverade i processen. Resultaten visade att de viktigaste variablerna var frånvaro, tidigare betyg och resultat från Stockholmsprovet (kommunal matematikdiagnos). Vidare var variabler från lärplattformen en viktig indikator ifall lärplattformen användes av läraren. Algoritmens noggrannhet indikerade en positiv trend för att klassificeringen gjordes korrekt. Å andra sidan är det tveksamt ifall det förebyggande systemet kan användas i sitt nuvarande tillstånd då mängden data som användes för att träna algoritmen var liten. Därav är en slutsats att det är nödvändigt för vidare studier att öka mängden datapunkter som används. I Diskussionen nämns förslag på hur problemet ska åtgärdas. Dessutom analyseras resultaten tillsammans med en utvärdering av systemet från ett didaktiskt perspektiv. Vidare diskuteras rapportens etiska aspekter genomgående.
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Fluvial and climatic controls on tropical agriculture and adaptation strategies in data-scarce contextsSerrao, Livia 29 July 2022 (has links)
Over the past decades, public concern about global environmental change has grown, following the progressive increase in both frequency and intensity of extreme events. Even though the problem is global, it has proved to have very different societal and environmental impacts at local level, further widening the gap between disadvantaged and advantaged communities, according to the degree of vulnerability of their social, economic and environmental systems. Among the various anthropogenic activities, the agricultural sector is particularly linked to global environmental change by a two-way relationship: on the one hand, intensive mono-cultures, together with intensive livestock production, compromise the environment and produce huge CO$_2$ emissions (one of the most important factors behind global warming); on the other hand, smallholder farming is one of the most endangered sectors by global environmental change, precisely because it depends heavily on the natural resources of the territory, including favourable weather and climate. Scientific research, supported by international institutions, has been working on this subject for several decades, analysing phenomena at global and local scale and providing medium and long-term forecasts capable of directing economic and political strategies. Such complex investigations become even more complex in contexts lacking reliable environmental data, where their low-quality and low representativeness weaken their reliability, compromising the reliability of the outcomes as well. This thesis seeks to respond to the increasing need of realistically addressing environmental phenomena that threaten rural communities and the environment on which they depend in low-income countries, by investigating two of the main environmental factors affecting tropical farming practices: river-floodplain dynamics and climate change. Despite data-related constraints, the environment of tropical rural areas still provides a unique opportunity to study several near-natural processes, such as the morphodynamics of mostly free-flowing rivers. Especially in foothill regions, unconfined or partially confined conditions of tropical rivers allow evaluating the natural dynamics of erodible river corridors, with erosion and accretion shaping their interactions with the adjacent floodplain and related human activities. At the same time, the complex terrain characterizing the river valleys at the foothills of high mountain chains also offers the opportunity to study interesting local meteorological processes, especially considering the interaction between synoptic-scale dynamics and local convective phenomena. In this context, local bottom-up initiatives and new and tailored-to-context strategies for adaptation to the ongoing environmental change are deepened following a multidisciplinary approach. This PhD research has been framed within an international cooperation project entitled “Sustainable Development and Fight against Climate Change in the Upper Huallaga basin (Peru)”, promoted by Mandacarù ONLUS, and funded by the Autonomous Province of Trento. The project aimed to enhance the resilience of the local farmers of the Upper Huallaga valley (Peru), facing the consequences of climate change and implementing new agricultural initiatives with a special attention to plantain and banana fields. Thanks to the support of the involved partners (Redesign by PROMER s.a.c., the Universidad Agraria Nacional de la Selva de Tingo Maria, in Peru, and the Edmund Mach Foundation of San Michele all’Adige, in Italy), the project provided the opportunity to carry out a consistent set of fieldwork activities over an 8-months period collecting hydro-morphological data, interviewing the local population, and installing two weather stations. The PhD thesis has been structured along two main parts, related to to the assessment of climate change effects on local agricultural practices, and the interplay between river-floodplain dynamics and floodplain agriculture. The part on the assessment of climate change includes two main research elements. First, a novel approach is used to evaluate climate change in data-scarce contexts: non-conventional data sources (population survey) are compared with conventional data sources (few local historical weather stations and global reanalysis data series – ERA5), to better account for the sub-daily time scale (local conventional sources only provide daily data), correlating weather changes perceived by farmers (more thunderstorms and longer drought periods) with climate variations deduced from quantitative data. Second, after having determined the most impacting meteorological variables on crops through the survey, a weather early-warning system has been developed to provide agro-meteorological forecasts to the \textit{bananeros} (banana farmers) of the Upper Huallaga valley. The system, based on the Weather Research and Forecasting (WRF) model, and enhanced with the assimilation of real-time observations from local meteorological stations installed during the project fieldwork, issues an alert when the predicted wind speed exceeds thresholds related to potential damage to the harvest, and spreads the warning via text messages. Such alerting system contains several novel features in relation to the socio-environmental context, allowing to discuss its potential for replication in analogous, vulnerable situations. The part on river-floodplain dynamics also includes two main research elements. First, a remote-sensing analysis is conducted at reach scale in two different reaches of the Huallaga River, quantifying geomorphological river trajectories and land use changes in the adjacent floodplain. The outcomes show that river morphology reacts differently depending on the agricultural systems (extensive or intensive) in the nearby floodplain, revealing a high geomorphological sensitivity of such a near-natural, highly dynamic river reach. Second, riverine agriculture within the erodible river corridor is analysed in association with riverine islands dynamics, at the geomorphic unit scale, evaluating the morphological evolution and agricultural suitability of two cultivated fluvial islands. The three main drivers of agricultural suitability within river erodible corridors, i.e. river disturbance, cultivation windows of opportunity, and soil suitability are quantified, allowing to generalize a process-based conceptual model of riverine islands as complex-adaptive-systems.
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Establishing a Real-time Precise Point Positioning Early Warning SystemQafisheh, Mutaz Wajeh Abdlmajid 29 July 2024 (has links)
[ES] Los sistemas de alerta temprana en tiempo real son instrumentos claves para vigilar posibles desastres geológicos como terremotos, tsunamis, actividades volcánicas, hundimiento del terreno o deslizamientos de ladera. Durante las últimas décadas, el número de personas afectadas por los diversos desastres geológicos ha aumentado de forma sustancial. Las consecuencias negativas de estos desastres afectan a la población y a las infraestructuras con diferentes niveles de gravedad, pudiendo llegar a tener un impacto elevado en pérdidas humanas y económicas. Sin embargo, los sistemas de alerta temprana tienen la capacidad de proporcionar avisos adecuados y confiables, lo que puede llevar a minimizar las pérdidas humanas y económicas.
El método de Posicionamiento Puntual Preciso en tiempo real (RT-PPP) desempeña un papel importante como parte de los sistemas de alerta temprana; debido a su capacidad para proporcionar seguimiento en tiempo real, cobertura global y su capacidad de obtención de mediciones precisas en tiempo real adquiridas por un solo receptor. A pesar de esto, el método (RT-PPP) utiliza productos para la corrección de la órbita y los relojes de los satélites (productos SSR) que son sensibles de los errores de la tecnología GNSS. Como consecuencia, estos errores pueden afectar la disponibilidad y fiabilidad de los sistemas de alerta temprana basados en la técnica RT-PPP. Debido a estos errores, se pueden llegar a generar avisos falsos, algunos de estos errores son: largos tiempos de inicialización, falta de continuidad y exactitud en los resultados, mala calidad de corrección de órbita y reloj de los satélites, mala resolución de la ambigüedad, etc. Además, la mala geometría de los satélites y la latencia de los productos SSR afectan gravemente el rendimiento del posicionamiento PPP en tiempo real.
Este trabajo de investigación, se enfoca, en una primera parte, en el análisis de los efectos y los métodos de mitigación de la latencia de los productos de corrección en tiempo real. El International GNSS Service (IGS) proporciona productos oficiales para materializar la técnica de PPP en tiempo real, estos productos contienen correcciones para las órbitas y los relojes de los satélites que se generan como combinación de los calculados en los diferentes centros de cálculo repartidos por el mundo. Este proceso de combinación aumenta la latencia y, por tanto, su impacto en la solución RT-PPP, afectando el desempeño de cualquier sistema de alerta temprana basada en RT-PPP. Así, en esta tesis, se usará el enfoque de Aprendizaje Automático para resolver el problema de la latencia, intentando predecir los valores de las correcciones en los productos SSR para el tiempo de la latencia. Se han utilizado los modelos de Support Vector Regression (SVR) y de media móvil integrada autorregresiva (ARIMA) para la predicción, necesitando, en el proceso, la implantación de ventanas deslizantes para entrenar y parametrizar los modelos de aprendizaje automático.
En cuanto al desempeño del sistema RT-PPP de alerta temprana, este trabajo de investigación ha evaluado, estadísticamente, varios modelos de aprendizaje automático, entre ellos los métodos de Árbol de decisión, Random Forest, Máquina de vectores de soporte (SVM), K vecinos más cercanos, Regresión logística, y el modelo de boosting extremo por gradientes (XGB). El análisis de los resultados indica que los modelo de XGB y Random Forest muestran los resultados más coherentes y precisos con 97 y 99 porciento de precisión. Asimismo, el modelo XGB muestra menos tendencia a iniciar falsas alarmas con un 2,48 por ciento en comparación con el 16,28 por ciento del modelo Random Forest.A partir de los resultados de la investigación, se derivan un conjunto de pruebas estadísticas para evaluar el desempeño de los sistemas de alerta temprana establecidos. Estas pruebas estadísticas pueden evaluar la capacidad de los modelos de aprendizaje automático utilizados con a la detecciónde deformaciones. / [CA] Els sistemes d'alerta primerenca en temps real són instruments claus per vigilar possibles desastres geològics com ara terratrèmols, tsunamis, activitats volcàniques, enfonsament del terreny o lliscaments de vessant. Durant les darreres dècades, el nombre de persones afectades pels diversos desastres geològics ha augmentat de manera substancial. Les conseqüències negatives d'aquests desastres afecten la població i les infraestructures amb diferents nivells de gravetat i poden arribar a tenir un impacte elevat en pèrdues humanes i econòmiques. Tot i això, els sistemes d'alerta primerenca tenen la capacitat de proporcionar avisos adequats i fiables, la qual cosa pot portar a minimitzar les pèrdues humanes i econòmiques.
El mètode de Posicionament Puntual Precís en temps real (RT-PPP) té un paper important com a part dels sistemes d'alerta primerenca; a causa de la seva capacitat per proporcionar seguiment en temps real, cobertura global i la seva capacitat d'obtenció de mesuraments precisos en temps real adquirits per un sol receptor.Tot i això, el mètode RT-PPP utilitza productes per a la correcció de l'òrbita i els rellotges dels satèl·lits (productes SSR) que són sensibles als errors de la tecnologia GNSS. Com a conseqüència, aquests errors poden afectar la disponibilitat i la fiabilitat dels sistemes d'alerta primerenca basats en la tècnica RT-PPP. A causa d'aquests errors, es poden arribar a generar avisos falsos, alguns d'aquests errors són: llargs temps d'inicialització, manca de continuïtat i exactitud als resultats, mala qualitat de correcció d'òrbita i rellotge dels satèl·lits, mala resolució de l'ambigüitat, etc. A més, la mala geometria dels satèl·lits i la latència dels productes SSR afecten greument el rendiment del posicionament PPP en temps real.
Aquest treball de recerca s'enfoca, en una primera part, a l'anàlisi dels efectes i els mètodes de mitigació de la latència dels productes de correcció en temps real. L'International GNSS Service (IGS) proporciona productes oficials per materialitzar la tècnica de PPP en temps real, aquests productes contenen correccions per a les òrbites i els rellotges dels satèl·lits que es generen com a combinació dels calculats als diferents centres de càlcul repartits pel món. Aquest procés de combinació augmenta la latència i, per tant, el seu impacte en la solució RT-PPP, afectant l'exercici de qualsevol sistema d'alerta primerenca basada en RT-PPP. Així, en aquesta tesi, s'usarà l'enfocament d'aprenentatge automàtic (Machine Learning) per resoldre el problema de la latència, intentant predir els valors de les correccions en els productes SSR per al temps de la latència. S'han utilitzat els models de Support Vector Regression (SVR) i de mitjana mòbil integrada autoregressiva (ARIMA) per a la predicció, necessitant, en el procés, la implantació de finestres lliscants per entrenar i parametritzar els models d'aprenentatge automàtic.
Els resultats de la investigació de la part de la latència han indicat que els models SVR i ARIMA podran mitigar la influència de la latència per als principals sistemes de navegació per satèl·lit (GPS i GLONASS) al voltant d'un vint per cent. El model SVR va mostrar una lleugera tendència a predir valors atípics; tot i això, el temps d'execució del SVR és significativament menor que el temps de processament del model ARIMA. Pel que fa a desenvolupament del sistema RT-PPP d'alerta primerenca, aquest treball de recerca ha avaluat, estadísticament, diversos models d'aprenentatge automàtic, entre ells els mètodes d'Arbre de Decisió, Random Forest, Màquina de Vectors de Suport (SVM), K veïns més propers, Regressió Logística, i el model de Boosting Extrem per gradients (XGB).L'anàlisi dels resultats indica que els models de XGB i Random Forest mostren els resultats més coherents i precisos amb 97i99 porcent de precisió respectivament. Així mateix, el model XGB mostra menys tendència a iniciar falses alarmes amb un 2,48% en comparació del 16,28% del model RF. / [EN] Real-Time Early Warning Systems are a critical approach implemented for monitoring geo-hazard disasters such as earthquakes, tsunamis, volcanic activities, and land subsidence. The Earth's population has experienced a substantial increasement, consequently exposing a growing number of people to the effects of various geo-hazard disasters. These influences could impact citizens and countries at different severity levels, reaching high costs in terms of human beings and economic losses. However, the early warning system's ability to initiate proper and reliable warnings significantly impacts in disaster cost reductions in terms of saving lives, reducing home and infrastructure damages, and mitigating economic losses.
Real-Time Precise Point Positioning (RT-PPP) plays a significant role as part of the Early Warning Systems, due to its potential to provide real-time tracking and global coverage and its reliance on precise real-time measurements acquired from only one receiver. However, the RT-PPP approach applies State Space Representation (SSR) products that are highly sensitive to several GNSS error sources. As a result, the warning system's availability and reliability are negatively impacted. It may even be triggered to issue false warnings by factors such as long initialization times, convergence losses, due to poor quality of orbital and clock corrections, ambiguity resolutions, or/and multipath error. Furthermore, poor satellite geometry and the latency of SSR products severely affect the performance of real-time PPP positioning.
In this research, we investigated the effect and mitigation of latency on real-time correction products. The International GNSS Services (IGS) provides official real-time products for RT-PPP; these products contain clock and orbit corrections, among others, and they are the main research concerns as the combination process increases the latency impact on both RT-PPP results and influences the early warning systems performance based on this positioning technique. In this research, investigations into the potentiality of using machine learning approaches to overcome latency problems were carried out. The research examines the Support Vector Regression (SVR) and Autoregressive Integrated Moving Average (ARIMA) machine learning models to predict the corrections broadcasted in SSR products that have a big capability in order to be used instead of the corrections impacted with latency
The research results regarding latency showed that the SVR and ARIMA models could mitigate the latency influences for the primary navigation satellite systems GPS and GLONASS by around twenty percent. The SVR model showed a tendency to predict outliers; however, the execution time for the SVR is significantly faster than the ARIMA model processing time.
Regarding the performance of the RT-PPP early warning system, the research statistically evaluates several machine learning models, including decision tree, random forest, support vector classifier, K nearest neighbors, logistic regression, and extreme gradient boosting models as machine learning approaches for establishing an early warning system. The extreme gradient boosting and random forest models were more accurate than the other utilized models, with 97 and 99 percent overall accuracy. At the same time, the extreme gradient boosting showed less tendency to initiate false alarms, with 2.48 percent compared to 16.28 percent for the random forest model.
From the research findings, we derived a set of statistical assessments to evaluate the performance of the established early warning systems. These statistical assessments can evaluate the ability of the utilized machine learning models regarding deformation detections and the model's tendency to initiate false warnings. The study's results confirmed that extreme gradient boosting is the most effective machine learning technique for creating an early warning system. / Qafisheh, MWA. (2024). Establishing a Real-time Precise Point Positioning Early Warning System [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/206740
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理性選擇、社會資本與全球減災合作:印度洋海嘯預警系統個案分析 / Rational choice, social capital, and global cooperation in disaster reduction: A Case study on Indian ocean tsunami warning system (IOTWS)王俊元, Wang, Chun Yuan Unknown Date (has links)
根據世界銀行的資料顯示,佔全球面積約19%的2500萬平方公里之地球表面,及佔全球一半以上人口的34億人是相對的暴露在一個以上天然災害之威脅下。隨著全球化的來臨,我們居住在一個風險共享的社會中,而在全球環境安全被視為全球公共財的同時,如何在集體行動的邏輯下進行全球危機管理,已成為全球行動者的主要課題。例如如何透過國際合作來對抗SARS,禽流感等危機,皆是當前全球行動者關注的議題。值得注意的是,儘管近二十年來國際社會對於減災所做的承諾與投入的資源日益增加,災害所造成的經濟損失及受到災害影響之人口卻也逐漸上升。面對這些現象,本研究最主要想要探究的研究問題即在於什麼樣的因素影響著全球減災合作。
本研究主要的研究問題,係探求在全球行動者為何要參與減災合作,而此全球減災合作又如何運作的呢?全球減災合作、理性選擇與全球社會資本的分析架構將被運用。從理論上粹取的因素,例如風險意識、能力素養、偏好、制度限制、資訊、可信的承諾與信任等,被用來分析行動者如何決定參與合作,以及此合作如何運作。鑑於2004年印度洋海嘯所造成的重大傷亡以及後續國際社會對救災及減災的承諾,本研究將以印度洋海嘯預警系統的個案為例,並透過在4個國家共計22人次對參與此系統的國際行動者之訪談資料,以及對參與印度洋海嘯預警系統之人員發放共計591份問卷進行調查及分析,回收問卷目前共計61份,然進行論文分析時為59份。換言之,實際上的回收率為10.66%,而本研究用以分析之問卷回收率為10.32%。本研究最主要的發現為風險意識及能力素養的提升,結合理性選擇與社會資本的不同因素作用下,將對全球減災合作的結果有正面的影響。最後,本研究也對未來國際減災合作提出相關之建議。 / Writing on the issue of global environmental security, the World Bank has noted that approximately “25 million square kilometers (about 19 percent of the Earth’s land area) and 3.4 billion people (more than half of the world’s population) are relatively highly exposed to at least one hazard.” With the coming of the globalization era, we .also live in a shared risk society. Since global environmental security is seen as a global public good, how to act for global crisis management under the logic of collective action has become a primary subject for global actors. Coping with the crises of SARS or Bird Flu through international cooperation has become a significant issue for these global actors. One of the main dilemmas of international cooperation for disaster reduction is the reconciliation of different individual actions. Interestingly, in spite of two decades efforts of international cooperation, the amount of damage caused by natural disasters and the total number if people affected have gradually increased since the 1960s.
This research focuses on two questions in the present research: why do global actors cooperate in disaster reduction, and how does this cooperation operate? The frameworks of international cooperation in disaster reduction, rational choice and global social capital are employed here, to explore the issue of international cooperation. Several factors, such as awareness of risk, capacity, preferences, institutional constraints, information, credible commitment, and trust, are used to examine how an actor engages in decision-making and how cooperation occurs.
Because of the tremendous damage that resulted from the Indian Ocean tsunami of 2004 and the engagement of the global society in disaster recovery and reduction, the above issues will be explored through a case study of the development of the Indian Ocean Tsunami Warning System (IOTWS). Twenty-two interviews were conducted in four countries and these constitute the qualitative data for this analysis. 591 questionnaires also have been sent to the participants in the IOTWS to collect the quantitative data. I analyzed the quantitative data from 59 returned questionnaires (10.32% returning rate) and the qualitative data from 22 interviewees in four countries. These analyses resulted in several suggestions to facilitate international cooperation for disaster reduction.
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Essays on Food Security in Sub-Saharan Africa : the role of food prices and climate shocks / Essais sur la sécurité alimentaire en Afrique sub-saharienne : le rôle des prix des denrées alimentaires et des chocs climatiquesBrunelin, Stéphanie 13 January 2014 (has links)
La crise alimentaire de 2008 a suscité un regain d’intérêt pour les questions agricoles et de sécurité alimentaire dans les pays en développement. Partant du constat que près de 27% de la population d’Afrique Sub-saharienne souffre de malnutrition, cette thèse a pour objectif de contribuer à une meilleure compréhension des causes complexes de l’insécurité alimentaire. Le premier chapitre étudie les mécanismes de transmission des variations du prix mondial du riz aux prix domestiques dans trois pays ouest-africain: le Sénégal, le Tchad et le Mali. Les résultats indiquent que le prix du riz importé à Dakar et le prix du riz local à Bamakorépondent de façon asymétrique aux variations du prix mondial. Le chapitre 2 teste la présence d’obstacles aux échanges agricoles entre pays d’Afrique de l’Ouest et du Centre. Il ressort de l’analyse que le passage des frontières est coûteux. Toutefois, le coût associé au passage de la frontière est plus faible entre pays membre d’une même union économique et monétaire. Le chapitre 3 a pour objectif le renforcement des systèmes d’alertes précoces des crises alimentaires existants au Sahel. Il montre qu’il est possible d’anticiper les crises de prix avec six mois d’avance en analysant les mouvements passés des prix des céréales. Enfin, le chapitre 4 s’intéresse à la vulnérabilité des ménages face aux chocs pluviométriques. Il révèle que les ménages ruraux au Burkina Faso n’ont pas la capacité d’assurer ou d’absorber ces chocs climatiques. / This doctoral thesis is in line with the renewed interest in research on agriculture and food security, following the 2008 global food crisis. The aim of this thesis is to contribute to a better understanding of the complex issues surrounding food security. The first chapter investigates whether the changes in the international price of rice are transmitted to the domestic prices of rice in Senegal, Mali and Chad. Results indicate that the domestic prices of imported rice in Dakar and of local rice in Bamako react differently to changes in the world price depending on whether the world price is rising or falling. Chapter 2 analyses by how much trade barriers at the border and transport costs impede the integration of agricultural markets in West and Central Africa. Results highlight the role played by borders in explaining price deviations between markets. Additionally, belonging to an economic union and sharingthe same currency appear as major determinants of market integration. The third chapter aims at providing new early warning indicators based on food prices in Mali, Niger and Burkina Faso. Our analysis reveals that price crisis can be predicted about 6 months in advance through the observation of past price movements. Chapter 4 focuses on the analysis of children’s vulnerability to climate shocks in Burkina Faso. By combining health data originating from a 2008 household survey with meteorological data, we show the importance of weather conditions in prenatal period and in the first year of life on the future nutritional status of the children.
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Forecast-based Humanitarian Action and Conflict : Promises and pitfalls of planning for anticipatory humanitarian response to armed conflictHostetter, Loic January 2019 (has links)
Practitioners of Forecast-based Action (FbA) argue that a humanitarian response able to utilize forecasts to accurately predict disaster, secure funding, and take action before the onset of a crisis will benefit donors and beneficiaries alike. In search of effective and efficient early-action regimes, a number of major humanitarian actors are developing FbA projects of various designs, predominantly in response to natural disaster and famine. While numerous organizations and institutions have expressed interest in developing FbA mechanisms, the tool has only been applied in a limited capacity to the humanitarian needs generated by armed conflict. This research seeks to understand whether a scalable FbA approach can be developed to stage principled, anticipatory humanitarian action in response to situations in which rigorous evaluations predict the likelihood of imminent armed conflict. The hypothesis is that the application of FbA to armed conflict is possible, but due to the complex political nature of conflict, implementing organizations should try to focus on creating mechanisms managed by humanitarian actors and, in so far as possible, be insulated from outside influence. This research is the first academic work to specifically investigate the application of FbA to armed conflict. Following an extensive review of current FbA mechanisms and conflict early warning practices, this research concludes that a conflict-centered FbA system akin to the automated FbA systems in use today to respond to natural disaster and famine is possible, but that the endeavor presents many practical and conceptual barriers to implementation. In particular, diffuse models such as the Start Fund offer a hopeful glimpse at a type of horizontal, member-driven FbA mechanism that is both highly context-sensitive and relatively insulated from outside influence. Such a design, however, features notable and inherent limitations in its ability to reliably and accurately predict the outbreak of conflict and respond in a manner that minimizes regretful actions.
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Econometric Methods for Financial Crises / Méthodes Econométriques pour les Crises FinancièresDumitrescu, Elena 31 May 2012 (has links)
Connus sous le nom de Systèmes d’Alerte Avancés, ou Early Warning Systems (EWS), les modèles de prévision des crises financières sont appelés à jouer un rôle déterminant dans l’orientation des politiques économiques tant au niveau microéconomique qu’au niveau macroéconomique et international. Or,dans le sillage de la crise financière mondiale, des questions majeures se posent sur leur réelle capacité prédictive. Deux principales problématiques émergent dans le cadre de cette littérature : comment évaluer les capacités prédictives des EWS et comment les améliorer ?Cette thèse d’économétrie appliquée vise à proposer (i) une méthode d’évaluation systématique des capacités prédictives des EWS et (ii) de nouvelles spécifications d’EWS visant à améliorer leurs performances. Ce travail comporte quatre chapitres. Le premier propose un test original d’évaluation des prévisions par intervalles de confiance fondé sur l’hypothèse de distribution binomiale du processus de violations. Le deuxième chapitre propose une stratégie d’évaluation économétrique des capacités prédictives des EWS. Nous montrons que cette évaluation doit être fondée sur la détermination d’un seuil optimal sur les probabilités prévues d’apparition des crises ainsi que sur la comparaison des modèles.Le troisième chapitre révèle que la dynamique des crises (la persistance) est un élément essentiel de la spécification économétrique des EWS. Les résultats montrent en particulier que les modèles de type logit dynamiques présentent de bien meilleurs capacités prédictives que les modèles statiques et que les modèles de type Markoviens. Enfin, dans le quatrième chapitre nous proposons un modèle original de type probit dynamique multivarié qui permet d’analyser les schémas de causalité intervenant entre différents types crises (bancaires, de change et de dette). L’illustration empirique montre clairement que le passage à une modélisation trivariée améliore sensiblement les prévisions pour les pays qui connaissent les trois types de crises. / Known as Early Warning Systems (EWS), financial crises forecasting models play a key role in definingeconomic policies at microeconomic, macroeconomic and international level. However, in the wake ofthe global financial crisis, numerous questions with respect to their forecasting abilities have been raised,as very few signals were drawn prior to the starting of the turmoil. Two questions arise in this context:how to evaluate EWS forecasting abilities and how to improve them?The broad goal of this applied econometrics dissertation is hence (i) to propose a systematic model-free evaluation methodology for the forecasting abilities of EWS as well as (ii) to introduce new EWSspecifications with improved out-of-sample performance. This work has been concretized in four chapters.The first chapter introduces a new approach to evaluate interval forecasts which relies on the binomialdistributional assumption of the violations series. The second chapter proposes an econometric evaluationmethodology of the forecasting abilities of an EWS. We show that adequate evaluation must take intoaccount the cut-off both in the optimal crisis forecast step and in the model comparison step. The thirdchapter points out that crisis dynamics (persistence) is essential for the econometric specification of anEWS. Indeed, dynamic logit models lead to better out-of-sample forecasting probabilities than those oftheir main competitors (static model and Markov-switching one). Finally, a multivariate dynamic probitEWS is proposed in the fourth chapter to take into account the causality between different types of crises(banking, currency, sovereign debt). The empirical application shows that the trivariate model improvesforecasts for countries that underwent the three types of crises.
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Adaptive EyesWege, Claudia 10 April 2015 (has links) (PDF)
Technology pervades our daily living, and is increasingly integrated into the vehicle – directly affecting driving. On the one hand technology such as cell phones provoke driver distraction and inattention, whereas, on the other hand, Advanced Driver Assistance Systems (ADAS) support the driver in the driving task. The question is, can a driver successfully adapt to the ever growing technological advancements?
Thus, this thesis aimed at improving safe driver behaviour by understanding the underlying psychological mechanisms that influence behavioural change. Previous research on ADAS and human attention was reviewed in the context of driver behavioural adaptation. Empirical data from multiple data sources such as driving performance data, visual behaviour data, video footage, and subjective data were analyzed to evaluate two ADAS (a brake-capacity forward collision warning system, B-FCW, and a Visual Distraction Alert System, VDA-System).
Results from a field operational test (EuroFOT) showed that brake-capacity forward collision warnings lead to immediate attention allocation toward the roadway and drivers hit the brake, yet change their initial response later on by directing their eyes toward the warning source in the instrument cluster. A similar phenomenon of drivers changing initial behaviour was found in a driving simulator study assessing a Visual Distraction Alert System. Analysis showed that a Visual Distraction Alert System successfully assists drivers in redirecting attention to the relevant aspects of the driving task and significantly improves driving performance. The effects are discussed with regard to behavioural adaptation, calibration and system acceptance. Based on these findings a novel assessment for human-machine-interaction (HMI) of ADAS was introduced.
Based on the contribution of this thesis and previous best-practices, a holistic safety management model on accident prevention strategies (before, during and after driving) was developed. The DO-IT BEST Feedback Model is a comprehensive feedback strategy including driver feedback at various time scales and therefore is expected to provide an added benefit for distraction and inattention prevention. The central contributions of this work are to advance research in the field of traffic psychology in the context of attention allocation strategies, and to improve the ability to design future safety systems with the human factor in focus. The thesis consists of the introduction of the conducted research, six publications in full text and a comprehensive conclusion of the publications.
In brief this thesis intends to improve safe driver behaviour by understanding the underlying psychological mechanisms that influence behavioral change, thereby resulting in more attention allocation to the forward roadway, and improved vehicle control. / Technologie durchdringt unser tägliches Leben und ist zunehmend integriert in Fahrzeuge – das Resultat sind veränderte Anforderungen an Fahrzeugführer. Einerseits besteht die Gefahr, dass er durch die Bedienung innovativer Technologien (z.B. Mobiltelefone) unachtsam wird und visuell abgelenkt ist, andererseits kann die Nutzung von Fahrerassistenzsystemen die den Fahrer bei der Fahraufgabe unterstützten einen wertvollen Beitrag zur Fahrsicherheit bieten. Die steigende Aktualität beider Problematiken wirft die Frage auf: "Kann der Fahrer sich erfolgreich dem ständig wachsenden technologischen Fortschritt anpassen?"
Das Ziel der vorliegenden Arbeit ist der Erkenntnisgewinn zur Verbesserung des Fahrverhaltens indem der Verhaltensänderungen zugrunde liegende psychologische Mechanismen untersucht werden. Eine Vielzahl an Literatur zu Fahrerassistenzsystemen und Aufmerksamkeitsverteilung wurde vor dem Hintergrund von Verhaltensanpassung der Fahrer recherchiert. Daten mehrerer empirischer Quellen, z. B. Fahrverhalten, Blickbewegungen, Videomitschnitte und subjektive Daten dienten zur Datenauswertung zweier Fahrerassistenzsysteme.
Im Rahmen einer Feldstudie zeigte sich, dass Bremskapazitäts-Kollisionswarnungen zur sofortigen visuellen Aufmerksamkeitsverteilung zur Fahrbahn und zum Bremsen führen, Fahrer allerdings ihre Reaktion anpassen indem sie zur Warnanzeige im Kombinationsinstrument schauen. Ein anderes Phänomen der Verhaltensanpassung wurde in einer Fahrsimulatorstudie zur Untersuchung eines Ablenkungswarnsystems, das dabei hilft die Blicke von Autofahrern stets auf die Straße zu lenken, gefunden. Diese Ergebnisse weisen nach, dass solch ein System unterstützt achtsamer zu sein und sicherer zu fahren.
Die vorliegenden Befunde wurden im Zusammenhang zu Vorbefunden zur Verhaltensanpassung zu Fahrerassistenzsystemen, Fahrerkalibrierung und Akzeptanz von Technik diskutiert. Basierend auf den gewonnenen Erkenntnissen wurde ein neues Vorgehen zur Untersuchung von Mensch- Maschine-Interaktion eingeführt. Aufbauend auf den Resultaten der vorliegenden Arbeit wurde ein ganzheitliches Modell zur Fahrsicherheit und -management, das DO-IT BEST Feedback Modell, entwickelt. Das Modell bezieht sich auf multitemporale Fahrer-Feedbackstrategien und soll somit einen entscheidenen Beitrag zur Verkehrssicherheit und dem Umgang mit Fahrerunaufmerksamkeit leisten. Die zentralen Beiträge dieser Arbeit sind die Gewinnung neuer Erkenntnisse in den Bereichen der Angewandten Psychologie und der Verkehrspsychologie in den Kontexten der Aufmerksamkeitsverteilung und der Verbesserung der Gestaltung von Fahrerassistenzsystemen fokusierend auf den Bediener. Die Dissertation besteht aus einem Einleitungsteil, drei empirischen Beiträgen sowie drei Buchkapiteln und einer abschliessenden Zusammenfassung.
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Exchange rate regimes and crises : insights for developing and emerging market economies / Régimes de change et crises : perspectives pour les pays émergents et en voie de développementAndreou, Irene 09 December 2010 (has links)
L’objectif de ce travail est d’analyser les implications du choix de régime de change dans les pays émergents et en développement, ainsi que d’apporter des éclaircissements sur les facteurs jouant un rôle important dans le déclenchement des crises (de change, bancaires, financières…) dans ces pays. Pour cela, l’analyse se tourne, dans un premier temps, vers la question du choix de régime de change optimal. Cette partie du travail s’appuie principalement sur un grand nombre de travaux théoriques et empiriques traitant de cette question, pour mettre en lumière les implications de ce choix, tout en tenant compte des particularités du groupe de pays qui font l’objet de cette étude. Dans une deuxième partie nous nous intéressons aux crises et les facteurs qui jouent un rôle majeur dans leur incidence. Ainsi, après une revue des différents modèles de crises afin d’identifier les variables d’intérêt, nous construisons deux modèles de prédiction des crises, ou « d’alarme précoce ». Enfin, la troisième partie du travail rassemble les enseignements tirés des deux parties précédentes pour traiter d’une question qui prend une ampleur croissante dans ces pays : étant donné la logique d’intégration financière mondiale et les avantages présentés par un régime de changes flottants dans un tel contexte, de quelle manière un pays envisageant un sortie vers ce régime de change peut-il la planifier, et à quel moment doit-il l’entreprendre, pour réussir une sortie sans crise majeure, que nous qualifions de sortie « ordonnée » ? Pour répondre à cette question, nous nous appuyons sur des expériences passées qui nous permettent de construire un modèle identifiant les variables susceptibles d’accroître la probabilité d’une sortie ordonnée. Nous complétons ce modèle par quelques considérations supplémentaires qui constituent des conditions importantes à la réussite d’une sortie ordonnée. L’objectif est d’apporter des recommandations susceptibles de faciliter cette transition. / The aim of this work is to analyze the implications of exchange rate regime choice in developing and emerging market economies, as well as highlight the factors that play a major role in the incidence of crises (currency, banking, financial…) in these countries. With this aim in mind, we start our analysis by turning to the question of the choice of the optimal exchange rate regime. This part of our work draws on a large number of both theoretical and empirical works evoking this question in order to determine the implications of this choice, all the while keeping in mind the fact that this particular group of countries present certain characteristics that are usually absent in their industrial counterparts. The second part of our work concentrates more specifically on crises and the factors that play a major role in their occurrence. Therefore, following a brief overview of different crisis models in order to identify the variables of interest, we propose two models for crisis prediction, or “Early Warning Systems”. Finally, the third and final part of our work brings together the conclusions of the earlier parts in order to address an issue that is becoming increasingly important in developing and emerging market economies: given their greater integration in international financial and capital markets, as well as the incontestable advantages of a floating exchange rate regime in such a context, how can a country wishing to exit to a more flexible exchange rate arrangement undertake such a transition, and when, in order to achieve an “orderly” exit, that is, an exit that is not accompanied by a crisis? To answer this question we draw on past experiences to construct a model indentifying the economic variables that might increase the probability of an orderly exit. We complete this model with a number of additional considerations that have recently emerged as important preconditions for an orderly exit, in order to provide some useful policy recommendations facilitating this transition.
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Essais sur la prévision de la défaillance bancaire : validation empirique des modèles non-paramétriques et étude des déterminants des prêts non performants / Essays on the prediction of bank failure : empirical validation of non-parametric models and study of the determinants of non-performing loansAffes, Zeineb 05 March 2019 (has links)
La récente crise financière qui a débuté aux États-Unis en 2007 a révélé les faiblesses du système bancaire international se traduisant par l’effondrement de nombreuses institutions financières aux États-Unis et aussi par l’augmentation de la part des prêts non performants dans les bilans des banques européennes. Dans ce cadre, nous proposons d’abord d’estimer et de tester l’efficacité des modèles de prévisions des défaillances bancaires. L’objectif étant d’établir un système d’alerte précoce (EWS) de difficultés bancaires basées sur des variables financières selon la typologie CAMEL (Capital adequacy, Asset quality, Management quality, Earnings ability, Liquidity). Dans la première étude, nous avons comparé la classification et la prédiction de l’analyse discriminante canonique (CDA) et de la régression logistique (LR) avec et sans coûts de classification en combinant ces deux modèles paramétriques avec le modèle descriptif d’analyse en composantes principales (ACP). Les résultats montrent que les modèles (LR et CDA) peuvent prédire la faillite des banques avec précision. De plus, les résultats de l’ACP montrent l’importance de la qualité des actifs, de l’adéquation des fonds propres et de la liquidité en tant qu’indicateurs des conditions financières de la banque. Nous avons aussi comparé la performance de deux méthodes non paramétriques, les arbres de classification et de régression (CART) et le nouveau modèle régression multivariée par spline adaptative (MARS), dans la prévision de la défaillance. Un modèle hybride associant ’K-means clustering’ et MARS est également testé. Nous cherchons à modéliser la relation entre dix variables financières et le défaut d’une banque américaine. L’approche comparative a mis en évidence la suprématie du modèle hybride en termes de classification. De plus, les résultats ont montré que les variables d’adéquation du capital sont les plus importantes pour la prévision de la faillite d’une banque. Enfin, nous avons étudié les facteurs déterminants des prêts non performants des banques de l’Union Européenne durant la période 2012-2015 en estimant un modèle à effets fixe sur données de panel. Selon la disponibilité des données nous avons choisi un ensemble de variables qui se réfèrent à la situation macroéconomique du pays de la banque et d’autres variables propres à chaque banque. Les résultats ont prouvé que la dette publique, les provisions pour pertes sur prêts, la marge nette d’intérêt et la rentabilité des capitaux propres affectent positivement les prêts non performants, par contre la taille de la banque et l’adéquation du capital (EQTA et CAR) ont un impact négatif sur les créances douteuses. / The recent financial crisis that began in the United States in 2007 revealed the weaknesses of the international banking system resulting in the collapse of many financial institutions in the United States and also the increase in the share of non-performing loans in the balance sheets of European banks. In this framework, we first propose to estimate and test the effectiveness of banking default forecasting models. The objective is to establish an early warning system (EWS) of banking difficulties based on financial variables according to CAMEL’s ratios (Capital adequacy, Asset quality, Management quality, Earnings ability, Liquidity). In the first study, we compared the classification and the prediction of the canonical discriminant analysis (CDA) and the logistic regression (LR) with and without classification costs by combining these two parametric models with the descriptive model of principal components analysis (PCA). The results show that the LR and the CDA can predict bank failure accurately. In addition, the results of the PCA show the importance of asset quality, capital adequacy and liquidity as indicators of the bank’s financial conditions. We also compared the performance of two non-parametric methods, the classification and regression trees (CART) and the newly multivariate adaptive regression splines (MARS) models, in the prediction of failure. A hybrid model combining ’K-means clustering’ and MARS is also tested. We seek to model the relationship between ten financial variables (CAMEL’s ratios) and the default of a US bank. The comparative approach has highlighted the supremacy of the hybrid model in terms of classification. In addition, the results showed that the capital adequacy variables are the most important for predicting the bankruptcy of a bank. Finally, we studied the determinants of non-performing loans from European Union banks during the period 2012-2015 by estimating a fixed effects model on panel data. Depending on the availability of data we have chosen a set of variables that refer to the macroeconomic situation of the country of the bank and other variables specific to each bank. The results showed that public debt, loan loss provisions, net interest margin and return on equity positively affect non performing loans, while the size of the bank and the adequacy of capital (EQTA and CAR) have a negative impact on bad debts.
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