920 resultados para Bayesian statistical decision theory
Resumo:
Emergency managers are faced with critical evacuation decisions. These decisions must balance conflicting objectives as well as high levels of uncertainty. Multi-Attribute Utility Theory (MAUT) provides a framework through which objective trade-offs can be analyzed to make optimal evacuation decisions. This paper is the result of data gathered during the European Commission Project, Evacuation Responsiveness by Government Organizations (ERGO) and outlines a preliminary decision model for the evacuation decision. The illustrative model identifies levels of risk at which point evacuation actions should be taken by emergency managers in a storm surge scenario with forecasts at 12 and 9 hour intervals. The results illustrate how differences in forecast precision affect the optimal evacuation decision. Additional uses for this decision model are also discussed along with improvements to the model through future ERGO data-gathering.
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We apply cooperative game theory concepts to analyze a Holt-Modigliani-Muth-Simon (HMMS) supply chain. The bullwhip effect in a two-stage supply chain (supplier-manufacturer) in the framework of the HMMS-model with quadratic cost functions is considered. It is assumed that both firms minimize their relevant costs, and two cases are examined: the supplier and the manufacturer minimize their relevant costs in a decentralized and in a centralized (cooperative) way. The question of how to share the savings of the decreased bullwhip effect in the centralized (cooperative) model is answered by the weighted Shapley value, by a transferable utility cooperative game theory tool, where the weights are for the exogenously given “bargaining powers” of the participants of the supply chain. = A cikkben a kooperatív játékelmélet fogalmait alkalmazzuk egy Holt-Mogigliani-Muth-Simon-típusú ellátási lánc esetében. Az ostorcsapás-hatás elemeit egy beszállító-termelő ellátási láncban ragadjuk meg egy kvadratikus készletezési és termelési költség mellett. Feltételezzük, hogy mindkét vállalat minimalizálja a releváns költségeit. Két működési rendszert hasonlítunk össze: egy hierarchikus döntéshozatali rendszert, amikor először a termelő, majd a beszállító optimalizálja helyzetét, majd egy centralizált (kooperatív) modellt, amikor a vállalatok az együttes költségüket minimalizálják. A kérdés úgy merül fel, hogy a csökkentett ostorcsapás-hatás esetén hogyan osszák meg a részvevők ebben a transzferálható hasznosságú kooperatív játékban a költség megtakarítást, exogén módon adott tárgyalási pozíció mellett.
Resumo:
Mennyiben képes jelenleg a közösségi gazdaságtan az adópolitikák nemzetek fölötti centralizációjára vonatkozó politikai döntések megalapozására? Válaszunk röviden az lesz, hogy a közösségi gazdaságtan főárama - noha számos releváns gazdasági és politikai tényező hatását sikeresen elemzi - jelenleg nem kínál kielégítőnek tekinthető döntési kritériumokat a döntéshozók számára. Ennek oka, hogy központi szerepet játszik benne egy, a modellek szempontjából exogén és a közgazdasági elmélettől idegen tényező: a kormányzatok jóindulatára, pontosabban annak mértékére vonatkozó premissza. Tanulmányunk az adóverseny fiskális föderalista elméletét vizsgálja, és megpróbál általánosabb szinten is a közszektor gazdaságelméletének jelenlegi állapotára, valamint továbbfejlesztésére vonatkozó tanulságokat levonni. A kiutat az elméleti zsákutcából a kormányzati működés és döntéshozatal, valamint a kívánatos gazdaságpolitikai döntések elméletének összekapcsolása jelentheti. Erre megtörténtek az első kísérletek, de a szisztematikus és átfogó elemzés egyelőre várat magára. / === / How far can community economics provide a basis for political decision-making on supranational centralization of taxation policies? The short answer here will be that although the mainstream of community economics succeeds in analysing many relevant economic and political factors, it fails at present to provide satisfactory criteria for decisionmakers. This is because a central role is played in it by a factor exogenous to the models and alien to economic theory: the premise of the measure of goodwill from governments. The study examines the fiscal federalist theory of tax competition. It tries to draw conclusions, on a more general level, about the present state of the economic theory of the public sector and future development of it. The way out of the theoretical blind alley could be to link the theories of government operation and decision-making and of desirable economic-policy decision-making. The first attempts to do so have been made, but a systematic and comprehensive analysis is still awaited.
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A szerző a megelégedésre törekvő döntéshozatalt és eszközeinek, az egyszerűsítő döntési stratégiáknak a hatékonysági kérdéseit tárgyalja. Az egyszerűsítő stratégiáknak és az alkalmazásukat támogató attitűdnek nemcsak az időt, hanem az információkeresés és - feldolgozás egyéb költségvonzatait is tekintetbe véve számos előnyük van. A szerző a szakirodalom rendszerezésével rávilágít az egyéni szintű leegyszerűsítések természetére és pozitív hatásaikra. A bevezetést és a meghatározásokat követően az egyszerűsítő stratégiák hatékonysági kérdéseit tárgyalja a környezeti tényezők függvényében, majd a döntéshozó személyiségét és pszichológiai jóllétét érintő összefüggésekről ír. A tanulmány végén folyamatban lévő empirikus kutatásának kérdéseire tér rá, mely kutatás az üzleti gyakorlat empirikus vizsgálatával kíván hozzájárulni az eddig főként laboratóriumi kísérletek eredményeire épülő tudáshoz. ___________ Placing itself in the domain of bounded rationality theory, the article deals with the advantages of satisficing and of using decision heuristics. As to the approach to decision heuristics, the author stands on the positive side, not focusing on biases, but showing interest in the effectiveness potential in heuristics. As a review of recent literature, the article deals with different advantages of satisficing and of using simplifying strategies, be it cognitive advantages, the effectiveness, or advantages concerning the psychological well-being of the decision maker. Actual research questions of the „adaptive toolbox” approach, and the problem of determination by personality traits are presented based on the review of recent research results. Further research directions are indicated after the review. By presenting his research questions the author shows how he is willing to enrich the results of this research program by his own empirical work.
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Herbert Simon, a korlátozott racionalitás elméletének megalkotója szerint a döntéshozatalunk hatékonyságát az határozza meg, hogy korlátozott kognitív kapacitásaink birtokában milyen stratégiákkal birkózunk meg a komplex környezet kihívásaival. Az erre az elméletre építő kutatások egyik alapvetése, hogy az egyéni problémamegoldási folyamat helyzetspecifikus és ez az idomulás kulcsfontosságú az eredményességben és hatékonyságban. A döntéshozó rendelkezik egy „adaptív szerszámosládával”, amelyből a megfelelő helyzetekben a megfelelő döntési eljárásokat választja. A tanulmányban a szerző egy kvalitatív kutatás eredményeire építve, a beszállítóválasztás példáján keresztül mutat be lehetséges válaszokat a keveset kutatott kérdésre: hogyan működik az adaptivitás folyamata? A tanulmány a döntési helyzethez való alkalmazkodás kialakulását vizsgálja a döntési folyamatok kognitív szintjén. ______ Herbert Simon, the author of theory of bounded rationality claimed that the results of our decision-making is defined by the approprietness of strategies with which we handle the complexity of the environment with our bounded cognitive capacities. One of the main issues or research programs building on this theory is that problem solving is situation-specific, and the adjustment of strategies to actual situational factors is crucial for the effectiveness and efficiency of decision-making. The decision-maker possesses an „adaptive toolbox”, from which he chooses the right decision tools in the right situations. The author, based on the findnings of a qualitative study, presents possible answers to the not well-elaborated question: how does the process of adaptivity work? Forming of an adaptive mechanism is in the focus.
Resumo:
A könyvvizsgálati kockázat a téves auditjelentés kiadásának kockázata olyan esetekben, amikor a beszámoló lényeges hibás állítást tartalmaz. Ez a kockázat indirekt módon a hitelintézetek és pénzügyi vállalkozások működésében is megjelenik azokban az esetekben, amikor a lényeges hibás állítást a finanszírozott vállalkozás auditált beszámolója tartalmazza, amelynek az alapján finanszírozási döntést hoznak, vagy a finanszírozás folytatásáról a beszámolóban szereplő, hibás információkból számított hitelkovenánsok alapján döntenek. A könyvvizsgálat kockázatában a vizsgált gazdálkodó üzleti kockázatai tükröződnek vissza, ezért a kockázat felmérése és az ellenőrzés ennek alapján való megtervezése, majd végrehajtása kulcsfontosságú. Jelen tanulmány – kapcsolódva a Hitelintézeti Szemle 2011. évi 4. számához – szintén a kockázat és bizonytalanság témakörét tárgyalja, pontosabban ennek egy gyakorlati vetületét: a bizonyosságfüggvények (belief functions) alkalmazását a könyvvizsgálatban; mindezt a teljesség és a tankönyvszerű rendszerfelépítés igénye nélkül. A módszer ugyanis hazánkban szinte ismeretlen, nemzetközi viszonylatban viszont empirikus kutatásban is rámutattak már az alkalmazás lehetséges előnyeire a hagyományos valószínűségelméleten alapuló számszerű kockázatbecslésekkel szemben. Eszerint a bizonyosságfüggvények jobban reprezentálják a könyvvizsgálóknak a kockázatról alkotott képét, mint a valószínűségek, mert – szemben a hagyományos modellel – nem két, hanem három állapotot kezelnek: a pozitív bizonyíték létezését, a negatív bizonyíték létezését és a bizonyíték hiányának esetét. _______ Audit risk is the risk that the auditor expresses an inappropriate audit opinion when the fi nancial statements are materially misstated. This kind of risk indirectly appears in the fi nancial statements of fi nancial institutions, when the material misstatement is in the fi nanced entity’s statements that serve as a basis for lending decisions or when the decision is made based upon credit covenants calculated from misstated information. The risks of the audit process refl ect the business risks of the auditee, so the assessment of risks, and further the planning and performance of the audit based on it is of key importance. The current study – connecting to No 4 2011 of Hitelintézeti Szemle – also discusses the topic of risk and uncertainty, or to be more precise a practical implementation of the aforementioned: the application of belief functions in the fi eld of external audit. All this without the aim of achieving completeness or textbook-like scrutiny in building up the theory. While the formalism is virtually unknown in Hungary, on the international scene empirical studies pointed out the possible advantages of the application of the method in contrast to risk assessments based on the traditional theory of probability. Accordingly, belief functions provide a better representation of auditors’ perception of risk, as in contrast to the traditional model, belief functions deal with three rather than two states: the existence of supportive evidence, that of negative evidence and the lack of evidence.
Resumo:
Ez a tanulmány a projektvezetési szakirodalomban kialakult ismeretanyagot szem előtt tartva (noha tételesen nem hivatkozva arra) tárja fel azt a sajátos és tipikusnak nevezhető kontextust, amelyben a projektalapú szervezetek projektmarketing tevékenysége megnyilvánul. A tanulmány célja tehát nem magának a projektmarketingnek a kérdéskörére irányul, hanem elsősorban annak projektspecifikus kontextusára. Jellegét illetően a tanulmány spekulatív jellegű, vagyis lényegét tekintve nem empirikus kutatási eredményekből levont következtetésekre épül. _____ The author analyses the cognitive level of individual decisions by placing the adaptive decision-maker in the centre of interest. The main question is how do adaptive processes evolve and what factors determine the adaptive mechanism. The author builds on his own qualitative study conducted with the Grounded Theory Methodology in the SME sector. The supplier selection decision is chosen from the wide range of business decisions. From the research results the two elements of the adaptive mechanism – the metastructure and the attitude set –, the process of their evolution and the factors determining this process are presented. The findings here are a middle-range theory, which can be elaborated further, but they provide some interesting insights already.
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Strategy is highly important for organisational success and the achievement of competitive advantage. Strategy is dynamic and it depends on accurate individual decision-making from medium and high-level managers and executives. Since managers always formulate strategy, its formulation depends mostly on their assertive decisions. Making good decisions is a complex task, even more in today’s business world where a large quantity of information and a dynamic environment forces people to decide without having complete information. As Shafir, Simonson, & Tversky (1993) point out, "the making of decisions, both big and small, is often difficult because of uncertainty and conflict". In this paper the author will explain a basic theoretical framework about top manager's individual decision-making, showing how complex the process of making high-impact decisions is; then, he will compare this theory with one of the most important streams in strategic management, the Resource-Based View (RBV) of the firm. Finally, within the context of individual decision-making and the RBV stream, the author will show how individual decision makers in top management positions constitute a valuable, rare, non-imitable and non-substitutable resource that provides sustained competitive advantage.
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This thesis develops and validates the framework of a specialized maintenance decision support system for a discrete part manufacturing facility. Its construction utilizes a modular approach based on the fundamental philosophy of Reliability Centered Maintenance (RCM). The proposed architecture uniquely integrates System Decomposition, System Evaluation, Failure Analysis, Logic Tree Analysis, and Maintenance Planning modules. It presents an ideal solution to the unique maintenance inadequacies of modern discrete part manufacturing systems. Well established techniques are incorporated as building blocks of the system's modules. These include Failure Mode Effect and Criticality Analysis (FMECA), Logic Tree Analysis (LTA), Theory of Constraints (TOC), and an Expert System (ES). A Maintenance Information System (MIS) performs the system's support functions. Validation was performed by field testing of the system at a Miami based manufacturing facility. Such a maintenance support system potentially reduces downtime losses and contributes to higher product quality output. Ultimately improved profitability is the final outcome. ^
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Extreme stock price movements are of great concern to both investors and the entire economy. For investors, a single negative return, or a combination of several smaller returns, can possible wipe out so much capital that the firm or portfolio becomes illiquid or insolvent. If enough investors experience this loss, it could shock the entire economy. An example of such a case is the stock market crash of 1987. Furthermore, there has been a lot of recent interest regarding the increasing volatility of stock prices. ^ This study presents an analysis of extreme stock price movements. The data utilized was the daily returns for the Standard and Poor's 500 index from January 3, 1978 to May 31, 2001. Research questions were analyzed using the statistical models provided by extreme value theory. One of the difficulties in examining stock price data is that there is no consensus regarding the correct shape of the distribution function generating the data. An advantage with extreme value theory is that no detailed knowledge of this distribution function is required to apply the asymptotic theory. We focus on the tail of the distribution. ^ Extreme value theory allows us to estimate a tail index, which we use to derive bounds on the returns for very low probabilities on an excess. Such information is useful in evaluating the volatility of stock prices. There are three possible limit laws for the maximum: Gumbel (thick-tailed), Fréchet (thin-tailed) or Weibull (no tail). Results indicated that extreme returns during the time period studied follow a Fréchet distribution. Thus, this study finds that extreme value analysis is a valuable tool for examining stock price movements and can be more efficient than the usual variance in measuring risk. ^
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The physics of self-organization and complexity is manifested on a variety of biological scales, from large ecosystems to the molecular level. Protein molecules exhibit characteristics of complex systems in terms of their structure, dynamics, and function. Proteins have the extraordinary ability to fold to a specific functional three-dimensional shape, starting from a random coil, in a biologically relevant time. How they accomplish this is one of the secrets of life. In this work, theoretical research into understanding this remarkable behavior is discussed. Thermodynamic and statistical mechanical tools are used in order to investigate the protein folding dynamics and stability. Theoretical analyses of the results from computer simulation of the dynamics of a four-helix bundle show that the excluded volume entropic effects are very important in protein dynamics and crucial for protein stability. The dramatic effects of changing the size of sidechains imply that a strategic placement of amino acid residues with a particular size may be an important consideration in protein engineering. Another investigation deals with modeling protein structural transitions as a phase transition. Using finite size scaling theory, the nature of unfolding transition of a four-helix bundle protein was investigated and critical exponents for the transition were calculated for various hydrophobic strengths in the core. It is found that the order of the transition changes from first to higher order as the strength of the hydrophobic interaction in the core region is significantly increased. Finally, a detailed kinetic and thermodynamic analysis was carried out in a model two-helix bundle. The connection between the structural free-energy landscape and folding kinetics was quantified. I show how simple protein engineering, by changing the hydropathy of a small number of amino acids, can enhance protein folding by significantly changing the free energy landscape so that kinetic traps are removed. The results have general applicability in protein engineering as well as understanding the underlying physical mechanisms of protein folding. ^
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The purpose of the present dissertation was to evaluate the internal validity of symptoms of four common anxiety disorders included in the Diagnostic and Statistical Manual of Mental Disorders fourth edition (text revision) (DSM-IV-TR; American Psychiatric Association, 2000), namely, separation anxiety disorder (SAD), social phobia (SOP), specific phobia (SP), and generalized anxiety disorder (GAD), in a sample of 625 youth (ages 6 to 17 years) referred to an anxiety disorders clinic and 479 parents. Confirmatory factor analyses (CFAs) were conducted on the dichotomous items of the SAD, SOP, SP, and GAD sections of the youth and parent versions of the Anxiety Disorders Interview Schedule for DSM-IV (ADIS-IV: C/P; Silverman & Albano, 1996) to test and compare a number of factor models including a factor model based on the DSM. Contrary to predictions, findings from CFAs showed that a correlated model with five factors of SAD, SOP, SP, GAD worry, and GAD somatic distress, provided the best fit of the youth data as well as the parent data. Multiple group CFAs supported the metric invariance of the correlated five factor model across boys and girls. Thus, the present study’s finding supports the internal validity of DSM-IV SAD, SOP, and SP, but raises doubt regarding the internal validity of GAD.^
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This study investigated how students perceived their motivation in high school social studies classes in school and to determine if a correlation exists between students’ grade level, race, gender, and their motivation. The sample included 337 high school students in Broward County, Florida. To assess students’ perceptions on their motivation the academic self-regulation questionnaire was utilized. Results indicate that social studies students show high levels of external regulation, with a mean score at 22.31 on a scale of 36 points. The results show a mean score of 24 on a scale of 28 points for identified regulation among social studies students. Findings revealed that student motivation could be gauged. No statistical significance was found between high school students’ grade level, race, gender, and their motivation in social studies classes. The findings of this study have shown that students at Boyd H. Anderson High School want to learn social studies.
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Understanding how decisions for international investments are made and how this affects the overall pattern of investments and firm’s performance is of particular importance both in strategy and international business research. This dissertation introduced first home-host country relatedness (HHCR) as the degree to which countries are efficiently combined within the investment portfolios of firms. It theorized and demonstrated that HHCR will vary with the motivation for investments along at least two key dimensions: the nature of foreign investments and the connectedness of potential host countries to the rest of the world. Drawing on cognitive psychology and decision-making research, it developed a theory of strategic decision making proposing that strategic solutions are chosen close to a convenient anchor. Building on research on memory imprinting, it also proposed that managers tend to rely on older knowledge representation. In the context of international investment decisions, managers use their home countries as an anchor and are more likely to choose as a site for foreign investments host countries that are ‘close’ to the home country. These decisions are also likely to rely more strongly on closeness to time invariant country factors of historic and geographic nature rather than time-variant institutions. Empirical tests using comprehensive investments data by all public multinational companies (MNC) worldwide, or over 15,000 MNCs with over half a million subsidiaries, support the claims. Finally, the dissertation introduced the concept of International Coherence (IC) defined as the degree to which an MNE’s network comprises countries that are related. It was hypothesized that maintaining a high level of coherence is important for firm performance and will enhance it. Also, the presence of international coherence mitigates some of the negative effects of unrelated product diversification. Empirical tests using data on foreign investments of over 20,000 public firms, while also developing a home-host country relatedness index for up to 24,300 home-host pairs, provided support for the theory advanced.
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This study was conducted to understand (a) hospital social workers' perspectives about patients' personal autonomy and self-determination, (b) their experiences, and (c) their beliefs and behaviors. The study used the maximum variation sampling strategy to select hospitals and hospital social work respondents. Individual interviews were conducted with 31 medical/surgical and mental health hospital social workers who worked in 13 hospitals. The data suggest the following four points. First, the hospital setting as an outside influence as it relates to illness and safety, and its four categories, mentally alert patients, family members, health care professionals, and social work respondents, seems to enhance or diminish patients' autonomy in discharge planning decision making. Second, respondents report they believe patients must be safe both inside and outside the hospital. In theory, respondents support autonomy and self-determination, respect patients' wishes, and believe patients are the decision makers. However, in practice, respondents respect autonomy and self-determination to a point. Third, a model, The Patient's Decision in Discharge Planning: A Continuum, is presented where a safe discharge plan is at one end of a continuum, while an unsafe discharge plan is at the other end. Respondents respect personal autonomy and the patient's self-determination to a point. This point is likely to be located in a gray area where the patient's decision crosses from one end of the continuum to the other. When patients decide on an unsafe discharge plan, workers' interventions range from autonomy to paternalism. And fourth, the hospital setting as an outside influence may not offer the best opportunity for patients to make decisions (a) because of beliefs family members and health care professionals hold about the value of patient self-determination, and (b) because patients may not feel free to make decisions in an environment where they are surrounded by family members, health care professionals, and social work respondents who have power and who think they know best. Workers need to continue to educate elderly patients about their right to self-determination in the hospital setting. ^