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Causal Relationships (causal + relationships)
Selected AbstractsSense of Coherence and Mood States: Exploring the Causal RelationshipsJOURNAL OF APPLIED SOCIAL PSYCHOLOGY, Issue 1 2009Rivka Berger The current study seeks to explore the effect of an academic course on sense of coherence (SOC) and transitory mood states. Moreover, the causal relationships between SOC and transitory mood states was evaluated. Second-year pharmacology students completed pencil-and-paper questionnaires at the beginning of the semester and 3-1/2 months later. The study group (n = 37) participated in an academic course developed to teach cognitive behavior concept and practice, whereas the control group (n = 43) had additional sessions of laboratory work. SOC increased significantly after the course while tension,anxiety and confusion decreased significantly. Structural equation analyses in the study group suggested that SOC was modified by confusion and perceived stress. No such pattern was observed in the control group. [source] Disproving Causal Relationships Using Observational Data,OXFORD BULLETIN OF ECONOMICS & STATISTICS, Issue 3 2009Henry L. Bryant Abstract Economic theory is replete with causal hypotheses that are scarcely tested because economists are generally constrained to work with observational data. We describe a method for testing a hypothesis that one observed random variable causes another. Contingent on a sufficiently strong correspondence between the two variables, an appropriately related third variable can be employed for the test. The logic of the procedure naturally suggests strong and weak grounds for rejecting the causal hypothesis. Monte Carlo results suggest that weakly grounded rejections are unreliable for small samples, but reasonably reliable for large samples. Strongly grounded rejections are highly reliable, even for small samples. [source] Is the historical war against wildlife over in southern Europe?ANIMAL CONSERVATION, Issue 3 2009A. Martínez-Abraín Abstract Most southern European regions have experienced a rapid economical change during the last decades, moving from a historical economy based on agriculture to a society based on industry and technology. We test here whether causes of admission of birds admitted to a large southern European rehabilitation centre, during a 14-year period (1994,2007), reflect these socio-economical changes. Specifically, we estimated the trends in the number of birds admitted to the centre by shooting (S) over the number of birds admitted due to impacts caused by infrastructures (I), for the 10 most commonly admitted species with complete time series available. Species were grouped in three groups following ecological traits: raptors (diurnal and nocturnal) and aquatic birds. Trends were estimated by means of the slope of a linear regression of the log-transformed S/I ratio over time, which provided the finite population growth rate (,) and its 95% confidence intervals. We used the ratio to prevent possible biases caused by changes in wild population densities over the years. We conclude that the overall trend in the S/I ratio, as well as the trends for all three bird groups considered, were negative, and indicated a c. 10% annual reduction in the number of birds admitted by shooting in relation to those admitted by infrastructure-related injuries. Causal relationships were analysed by means of Poisson regressions on absolute numbers. Importantly we show that despite the direct historical war against wildlife seems to be coming to an end in southern Europe, impact to wildlife continues in an indirect way, as collateral damages caused by our post-industrial way of life. So the overall scenario is most likely not one of improved conservation status in southern Europe, but rather one of shifting ways of impacting wildlife in parallel with socio-economic changes. [source] Enhancing Knowledge Transfer in Classroom Versus Online Settings: The Interplay Among Instructor, Student, Content, and ContextDECISION SCIENCES JOURNAL OF INNOVATIVE EDUCATION, Issue 1 2009Louise Nemanich ABSTRACT This article integrates management education and organizational learning theories to identify the factors that drive the differences in student outcomes between the online and classroom settings. We draw upon theory on knowledge transfer barriers in organizations to understand the interlinking relationships among presage conditions, deep learning process, and product in the 3P model of student learning. We test our model in the context of undergraduate education and find that confidence in the instructor's expertise, perceived content relevance, and the social richness of the classroom learning environment enhance student enjoyment of the course. Confidence in instructor's expertise and perceived content relevance also contribute to greater understanding of causal relationships among course concepts. Enjoyment is positively associated with learning performance in the classroom, but not online, and student ability is positively associated with learning performance in the online context, but not in the classroom. Our results have implications for course designs in the traditional classroom context and the more innovative online environment. [source] Topical dose delivery in the reptilian egg treatment modelENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2007Jennifer K. Muller Abstract Developing assays to detect endocrine-mediated toxicity from in ovo or in utero exposure is a current challenge in regulatory toxicology. Some species of reptiles exhibiting a unique mode of sex determination, in which the incubation temperature during a critical period determines gonadal sex, have been explored as an in ovo model to screen environmental contaminants for endocrine effects. We critically review published egg-exposure studies and conclude that data regarding the pharmacokinetics of topically applied substances are insufficient to validate dose,response relationships for the effects of chemicals on in ovo endocrine function or gender determination in reptiles. The insufficiencies in these data largely result from methodological failures, including lack of measurement verification, failure to investigate and control extraneous factors affecting the measurements, and lack of independent replication of results. Considerable additional research will be necessary to alleviate these methodological inadequacies. Given the current status of the data, topical treatment of reptilian eggs cannot be considered to be a valid means of establishing causal relationships between chemical treatment and biological outcome. [source] Analytical ecological epidemiology: exposure,response relations in spatially stratified time seriesENVIRONMETRICS, Issue 6 2009Hagen Scherb Abstract An important task of environmental research is the investigation of a possible causal relationship between exposure and the frequency of a biologic trait. Major industrial accidents provide examples where the exposure status of large populations may change considerably within relatively short time intervals of days or weeks (e.g. Seveso herbicide plant explosion, Chernobyl Nuclear Power Plant catastrophe). Therefore, purely temporal change-points may be tested in time series of appropriate public health indicators (e.g. mortality, morbidity, sex ratio at birth). If, in addition, the spatial contamination is strong and variable enough and can be identified with sufficient precision at the level of regional units (e.g. districts), then a spatial-temporal approach makes sense. This essentially means that a global time trend model is adjusted for region-specific trend functions, allowing for local or global temporal jumps or broken sticks (change-points) at certain points in time. The local jump heights may be tested for associations with local exposure (exposure,response relation), and all other characteristics in the data that vary with locality and in time are automatically accounted for, thus minimizing confounding. Spatial-temporal approaches may help to strengthen the evidence of possible causal relationships. As an example, the human sex ratio at birth in several European countries before and after the Chernobyl Nuclear Power Plant accident was investigated. A long-term chronic impact of radioactive fallout on the secondary sex ratio has been found. Copyright © 2008 John Wiley & Sons, Ltd. [source] Sense of coherence and adjustment to divorce among Muslim Arab citizens of IsraelEUROPEAN JOURNAL OF PERSONALITY, Issue 4 2003Orna Cohen This study examined the distinctiveness and causal relationships of Antonovsky's (1979) Sense of Coherence Scale and the Mental Health Index of Veit and Ware (1983) in a sample of 306 divorced Muslim Arab men and women in Israel. The findings, based on confirmatory factor analysis and latent-variable structural modelling, suggest that in the present sample sense of coherence (SOC) and mental health are two independent but correlated constructs. They also suggest that, consistent with Antonovsky's theory, SOC may be better viewed as a mediator between stress and mental health than as a concurrent outcome of stress, although the latter possibility is not ruled out. Finally, the findings indicate that the SOC of the sample was relatively low in comparison with other groups. Copyright © 2003 John Wiley & Sons, Ltd. [source] The Impact of Life Events on Perceived Financial Stress, Clothing-Specific Lifestyle, and Retail Patronage: The Recent IMF Economic Crisis in KoreaFAMILY & CONSUMER SCIENCES RESEARCH JOURNAL, Issue 1 2000Soyeon Shim Using Andreasen's Model of Life Change Effects as a theoretical framework, the purpose of this study was to develop and test a model that depicts the direct and indirect influence of a life event, the Korean International Monetary Fund (IMF) crisis, on financial stress, clothing-specific lifestyle, and retail patronage behavior. A total of 502 females from two major metropolitan cities in Korea responded to a survey questionnaire. A structural equation modeling technique was used to test the hypotheses. Several statistical criteria supported theoretical, causal relationships among the measurement models in the study, providing strong support for Andreasen's model. More specifically, the IMF impact had affected retail patronage behavior directly as well as indirectly through clothing-specific lifestyles and financial stress. Both clothing-specific lifestyles and financial stress had an influence on retail patronage behavior. The IMF event had a stronger direct and total impact than financial stress on changes in retail patronage behavior. Theoretical and managerial implications are discussed. [source] Behavioural and physiological characterization of inbred mouse strains: prospects for elucidating the molecular mechanisms of mammalian learning and memoryGENES, BRAIN AND BEHAVIOR, Issue 2 2002P. V. Nguyen With the advent of recombinant DNA methodology, it has become possible to dissect the molecular mechanisms of complex traits, including brain function and behaviour. The increasing amount of available information on the genomes of mammalian organisms, including our own, has facilitated this research. The present review focuses on a somewhat neglected area of genetics, one that involves the study of inbred mouse strains. It is argued that the use of inbred mice is complementary to transgenic approaches in the analysis of molecular mechanisms of complex traits. Whereas transgenic technology allows one to manipulate a single gene and investigate the in vivo effects of highly specific, artificially induced mutations, the study of inbred mouse strains should shed light on the roles of naturally occurring allelic variants in brain function and behaviour. Systematic characterization of the behavioural, electrophysiological, neurochemical, and neuroanatomical properties of a large number of inbred strains is required to elucidate mechanisms of mammalian brain function and behaviour. In essence, a ,mouse phenome' project is needed, entailing the construction of databases to investigate possible causal relationships amongst the phenotypical characteristics. This review focuses on electrophysiological and behavioural characterization of mouse strains. Nevertheless, it is emphasized that the full potential of the analysis of inbred mouse strains may be attained if techniques of numerous disciplines, including gene expression profiling, biochemical analysis, and quantitative trait loci (QTL) mapping, to name but a few, are also included. [source] Primary Headache in Italian Early Adolescents: The Role of Perceived Teacher UnfairnessHEADACHE, Issue 3 2009Massimo Santinello BA Background., The impact of perceived teacher unfairness on headache incidence has previously been insufficiently investigated. Objective., The aims of the study are to analyze the prevalence of headache among Italian early adolescents as well as to examine the role of perceived teacher unfairness and classmate social support in predicting this health outcome. Methods., Data were taken from the "Health Behaviour in School Aged Children," a cross-sectional survey investigating health behaviors among early adolescents in selected European countries. Headache, perceived teacher unfairness, and classmate social support were measured through a self-administered questionnaire filled out by a representative sample of 4386 (48.4% males) Italian students (11, 13, and 15 years old). Covariates included demographic characteristics (age, gender) and socioeconomic status (parental educational attainment), and other confounding psychological factors (eg, family empowerment, bullying). Results., Prevalence of frequent headaches (at least once a week) was about 40%. Girls were more likely to report frequent headaches compared with boys. Prevalence of frequent headaches increased with age. After adjusting for age and gender, teacher unfairness showed a significant association with frequent headache (P < .001). This relationship remained significant even after additional adjustment for several psychosocial factors. Classmate social support seems to act as a protective factor, but not as a buffering mechanism against the negative effects of teacher unfairness. Conclusions., Italian early adolescents show a quite high prevalence of frequent headache. Results show that characteristics of the school setting, such as teacher unfairness and classmate social support, can be significant predictors of frequent headache among early adolescents. Longitudinal research is needed to delineate causal relationships between school factors and recurrent headache. [source] Psychosocial Impact of Headache and Comorbidity with Other Pains among Swedish School AdolescentsHEADACHE, Issue 8 2002Åsa Fichtel MSc Background.,The psychosocial impact of headache combined with other pains has previously been insufficiently investigated. Objective., The present study examined the prevalence of headache, its comorbidity with other pains and psychosocial impact among adolescents. Methods., 793 adolescents in a sample recruited from 8 schools in the middle of Sweden were assessed. Results.,Forty-five percent of the adolescents reported ongoing pain during assessment and more than half of the adolescents reported at least one frequent pain during the previous 6 months. The most common pain among girls was headache (42%), but for boys muscle pain (32%) was most prevalent. Number of pains and perceived pain disability were also higher among girls than boys. One-third of the headache sufferers had headache only, while one-third reported one other frequent pain and the others had at least two other frequent pains. Overall, adolescents with frequent headaches had higher levels of anxiety or depressive symptoms, in addition to functional disability and usage of analgesic medication. Frequent headache sufferers reported more problems in everyday life areas than those with infrequent headaches. Conclusions.,It is recommended that adolescents suffering from recurrent headaches routinely should be asked about the presence of other pains, anxiety and depressive symptoms, medication usage, in addition to psychosocial consequences in their everyday life activities. Longitudinal research is also needed to delineate causal relationships between psychosocial factors and recurrent pains, in particular regarding possible sex differences. [source] Comparison of commissural sprouting in the mouse and rat fascia dentata after entorhinal cortex lesionHIPPOCAMPUS, Issue 6 2003Domenico Del Turco Abstract Reactive axonal sprouting occurs in the fascia dentata after entorhinal cortex lesion. This sprouting process has been described extensively in the rat, and plasticity-associated molecules have been identified that might be involved in its regulation. To demonstrate causal relationships between these candidate molecules and the axonal reorganization process, it is reasonable to analyze knockout and transgenic animals after entorhinal cortex lesion, and because gene knockouts are primarily generated in mice, it is necessary to characterize the sprouting response after entorhinal cortex lesion in this species. In the present study, Phaseolus vulgaris -leucoagglutinin (PHAL) tracing was used to analyze the commissural projection to the inner molecular layer in mice with longstanding entorhinal lesions. Because the commissural projection to the fascia dentata is neurochemically heterogeneous, PHAL tracing was combined with immunocytochemistry for calretinin, a marker for commissural/associational mossy cell axons. Using both techniques singly as well as in combination (double-immunofluorescence) at the light or electron microscopic level, it could be shown that in response to entorhinal lesion mossy cell axons leave the main commissural fiber plexus, invade the denervated middle molecular layer, and form asymmetric synapses within the denervated zone. Thus, the commissural sprouting response in mice has a considerable translaminar component. This is in contrast to the layer-specific commissural sprouting observed in rats, in which the overwhelming majority of mossy cell axons remain within their home territory. These data demonstrate an important species difference in the commissural/associational sprouting response between rats and mice that needs to be taken into account in future studies. © 2003 Wiley-Liss, Inc. [source] Relationships among levels of government support, marketing activities, and financial health of nonprofit performing arts organizationsINTERNATIONAL JOURNAL OF NONPROFIT & VOLUNTARY SECTOR MARKETING, Issue 2 2007Theresa A. Kirchner This exploratory study researches and analyzes the empirical effects of financial levels of government support and marketing practices on the financial health of nonprofit performing arts organizations. Declining government subsidies and increasing competition from non-traditional sources have presented these organizations with unique opportunities and challenges that call for a market-centered, as well as an art-centered approach. Financial health is critical for the long-term success of a nonprofit performing arts organization. Few empirical studies have examined the interrelationships between these key variables. This study analyzes a sample of 63 American professional symphony orchestras employing 20 years of data. The correlations among financial levels of government support and marketing activities were positive and significant, the correlations among levels of government support and financial health were negative and significant, and the correlations between levels of marketing activity and financial health were negative and varied in significance. Causal analyses were less conclusive, but significant causal relationships were found for large symphony orchestras, indicating that segmentation research may be warranted. Implications and opportunities for future research are presented which have potential application for government agencies, academic researchers, and arts organization managers, boards of directors, and donors. Copyright © 2006 John Wiley & Sons, Ltd. [source] The effects of travel activities and seasons on expenditureINTERNATIONAL JOURNAL OF TOURISM RESEARCH, Issue 6 2005SooCheong (Shawn) Jang Abstract The primary objective of this research was to improve the understanding of the relationships among travel activities, seasons and expenditure after controlling for income. Path analysis was used to test all hypothesised causal relationships. In addition to its conceptual contributions, the findings of the study revealed how international travellers spend during travel in response to changes in activity preferences and season of travel. To maximise travellers' expenditure and to generate greater tourism revenues, destination policy-makers and marketers need to identify what types of activities and which season contribute most to their destination. Copyright © 2005 John Wiley & Sons, Ltd. [source] Geographic Mobility and Spatial Assimilation among U. S. Latino Immigrants,INTERNATIONAL MIGRATION REVIEW, Issue 3 2005Scott J. South Although the spatial assimilation of immigrants to the United States has important implications for social theory and social policy, few studies have explored the atterns and determinants of interneighborhood geographic mobility that lead to immigrants'residential proximity to the white, non-Hispanic majority. We explore this issue by merging data from three different sources - the Latino National Political Survey, the Panel Study of Income Dynamics, and tract-level census data - to begin unraveling causal relationships among indicators of socioeconomic, social, cultural, segmented, and spatial assimilation. Our longitudinal analysis of 700 Mexican, Puerto Rican, and Cuban immigrants followed from 1990 to 1995 finds broad support for hypotheses derived from the classical account of minority assimilation. High income, English language use, and embeddedness in Anglo social contexts increase Latino immigrants'geographic mobility into Anglo neighborhoods. U. S. citizenship and years spent in the United Stares are ppsidvely associated with geographic mobility into more Anglo neighbor oods, and coethnic contact is inversely associated with this form of mobility, but these associations operate largely through other redictors. Prior experiences of ethnic discrimination increase and residence in public housing decreases the likelihood that Latino immigrants will move from their origin neighborhoods, while residing in metropolitan areas with large Latino populations leads to geographic moves into "less Anglo" census tracts. [source] Causality and Causal Models: A Conceptual Perspective,INTERNATIONAL STATISTICAL REVIEW, Issue 3 2006Benito V. Frosini Summary This paper aims at displaying a synthetic view of the historical development and the current research concerning causal relationships, starting from the Aristotelian doctrine of causes, following with the main philosophical streams until the middle of the twentieth century, and commenting on the present intensive research work in the statistical domain. The philosophical survey dwells upon various concepts of cause, and some attempts towards picking out spurious causes. Concerning statistical modelling, factorial models and directed acyclic graphs are examined and compared. Special attention is devoted to randomization and pseudo-randomization (for observational studies) in view of avoiding the effect of possible confounders. An outline of the most common problems and pitfalls, encountered in modelling empirical data, closes the paper, with a warning to be very cautious in modelling and inferring conditional independence between variables. Résumé Le but de cet article est d'offrir une vue d'ensemble sur le thème des relations causales, à partir de la doctrine philosophique aristotélique, et ensuite étendues et formalisées dans le champ de l'analyse statistique multivarée. Dans la revue philosophique on analyse plusieurs conceptions de cause, et les essais de reconnâtre les causes "fausses". La partie centrale du travail s'occupe de modèles causals en forme graphique, qui constituent l'instrument électif de plusieurs recherches causales, et met en evidence la différence entre conditionnement et intervention sur une variable. On a dedié une particulière attention aux procédures de randomization dans le but d'éviter de possible confusions. L'article termine en conseillant d'user de la prudence dans la modelage de l'independence conditionnelle et dans son contrôl empirique. [source] The Philippine Land Reform in Comparative Perspective: Some Conceptual and Methodological ImplicationsJOURNAL OF AGRARIAN CHANGE, Issue 1 2006SATURNINO M. BORRAS JR Using empirical evidence from the Philippine land reform (1972,2005), this paper examines land reform theory and practice, and argues that convention has a priori excluded a significant portion of actually existing land-based production and distribution relationships, while it has inadvertently included in its definition and analysis land transfers that do not constitute real redistributive reform. This problematic framing of ,exclusion,inclusion' has led to incorrect accounting and analysis of the nature, scope, pace and direction of change/reform that have occurred (or not) in the agrarian structure of a particular setting. This problem has prevented the emergence of nuanced comparative land reform studies, with possible further implications for studies that attempt to trace causal relationships between land redistribution and agrarian transformation. [source] Sense of Coherence and Mood States: Exploring the Causal RelationshipsJOURNAL OF APPLIED SOCIAL PSYCHOLOGY, Issue 1 2009Rivka Berger The current study seeks to explore the effect of an academic course on sense of coherence (SOC) and transitory mood states. Moreover, the causal relationships between SOC and transitory mood states was evaluated. Second-year pharmacology students completed pencil-and-paper questionnaires at the beginning of the semester and 3-1/2 months later. The study group (n = 37) participated in an academic course developed to teach cognitive behavior concept and practice, whereas the control group (n = 43) had additional sessions of laboratory work. SOC increased significantly after the course while tension,anxiety and confusion decreased significantly. Structural equation analyses in the study group suggested that SOC was modified by confusion and perceived stress. No such pattern was observed in the control group. [source] Advanced relationships between categories analysis as a qualitative research toolJOURNAL OF CLINICAL PSYCHOLOGY, Issue 7 2010Merav Rabinovich Abstract The authors propose an advanced relationships between categories (RBC) model as an expansion of Tutty, Rothery, and Grinnell's (1996) qualitative tool for classifying RBC patterns as contained, temporal, and causal relationships. It is assumed that identification of the relationships obtained among categories of qualitative data paves the way for construction of a theory, even though few tools have been developed for this purpose to date. The advanced RBC model points to three additional relationship patterns: bilateral, trilateral, and quadrilateral relationships. These relationships reveal how the text itself links among its various components. The model serves as an innovative tool for systematic derivation of explanations based on the qualitative raw data, contributing to grounded theory and other interpretive studies. © 2010 Wiley Periodicals, Inc. J Clin Psychol: 66:1,11, 2010. [source] The ,reversal of fortune' thesis and the compression of history: Perspectives from African and comparative economic history,JOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 8 2008Gareth Austin Abstract Acemoglu, Johnson and Robinson have dramatically challenged the tendency of economists to confine their empirical search for the causes of economic growth to the recent past. They argue that the kind of institutions established by European colonialists, either protecting private property or extracting rents, resulted in the poorer parts of the pre-colonial world becoming some of the richest economies of today; while transforming some of the more prosperous parts of the non-European world of 1500 into the poorest economies today. This view has been further elaborated for Africa by Nunn, with reference to slave trading. Drawing on African and comparative economic historiography, the present paper endorses the importance of examining growth theories against long-term history: revealing relationships that recur because the situations are similar, as well as because of path dependence as such. But it also argues that the causal relationships involved are more differentiated than is recognised in AJR's formulations. By compressing different historical periods and paths, the ,reversal' thesis over-simplifies the causation. Relatively low labour productivity was a premise of the external slave trades; though the latter greatly reinforced the relative poverty of many Sub-Saharan economies. Again, it is important to distinguish settler and non-settler economies within colonial Africa itself. In the latter case it was in the interests of colonial regimes to support, rather than simply extract from, African economic enterprise. Finally, economic rent and economic growth have often been joint products, including in pre-colonial and colonial Africa; the kinds of institutions that favoured economic growth in certain historical contexts were not necessarily optimal for that purpose in others. AJR have done much to bring development economics and economic history together. The next step is a more flexible conceptual framework, and a more complex explanation. Copyright © 2008 John Wiley & Sons, Ltd. [source] Constructing a cognition map of alternative fuel vehicles using the DEMATEL methodJOURNAL OF MULTI CRITERIA DECISION ANALYSIS, Issue 1-2 2009Cheng-Wei Lin Abstract Environmental protection has taken serious notice of global warming. The Intergovernmental Panel on Climate Change (IPCC) has proved that CO2 is one of the factors for global warming. Furthermore, the majority of this emission comes from the vehicles using petroleum fuels. For this reason, alternative fuels become a very popular issue. There are many automakers and researchers endeavoring to develop alternative fuel vehicles (AFVs). There already have been many types of alternative fuels used in vehicles, such as electric vehicles (EVs), hybrid electric vehicles (HEVs), fuel cell (hydrogen) vehicles, natural gas vehicles (CNG), methanol vehicles, ethanol vehicles, and bio-diesel vehicles, etc. Different types of the alternative fuels have different characteristics to which attention should be paid. It is difficult for users to identify which one is the best choice for them to use. This problem concerns the characteristics of each alternative fuel. A lot of criteria and aspects related to the alternative fuels should be considered at the same time. In this study, we try to apply the Decision-Making Trial and Evaluation Laboratory (DEMATEL) method to deal with the importance and causal relationships among the evaluation factors of AFVs. Results show the top three critical evaluation criteria are ,new car cost', ,cruising range', and ,fuel efficiency'; ,air pollution' is the key cause factor influencing others; and ,cruising range' is the key effect factor influenced by others. It is no accident that cost is the most critical factor for users. Consequently, it is suggested to automakers and researchers to carefully analyze the characteristics of each alternative fuel. Fuel efficiency is not only focused on by users, but also it will affect the cruising range. Air pollution is what users care about, so even zero-emission vehicles (ZEVs), which cost more but have lower emission and higher fuel efficiency, could be accepted. There seems to be no perfect AFV, but to endeavor on ZEVs will reduce some disadvantages. Copyright © 2010 John Wiley & Sons, Ltd. [source] Price Dynamics in the International Wheat Market: Modeling with Error Correction and Directed Acyclic GraphsJOURNAL OF REGIONAL SCIENCE, Issue 1 2003David A Bessler In this paper we examine dynamic relationships among wheat prices from five countries for the years 1981,1999. Error correction models and directed acyclic graphs are employed with observational data to sort,out the dynamic causal relationships among prices from major wheat producing regions: Canada, the European Union, Argentina, Australia, and the United States. An ambiguity related to the cyclic or acyclic flow of information between Canada and Australia is uncovered. We condition our analysis on the assumption that information flow is acyclic. The empirical results show that Canada and the U.S. are leaders in the pricing of wheat in these markets. The U.S. has a significant effect on three markets excluding Canada. [source] Gender differences in science attitude-achievement relationships over time among white middle-school studentsJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 4 2002Nancy Mattern Four causal models describing the longitudinal relationships between attitudes and achievement have been proposed in the literature. These models feature: (a) cross-effects over time between attitudes and achievement, (b) influence of achievement predominant over time, (c) influence of attitudes predominant over time, or (d) no cross-effects over time between attitudes and achievement. In an examin-ation of the causal relationships over time between attitudes toward science and science achievement for White rural seventh- and eighth-grade students, the cross-effects model was the best fitting model form for students overall. However, when examined by gender, the no cross-effects model exhibited the most accurate fit for White rural middle-school girls, whereas a new model called the no attitudes-path model exhibited the best fit for these boys. © 2002 Wiley Periodicals Inc. J Res Sci Teach 39: 324,340, 2002 [source] The ubiquitous role of zinc in health and diseaseJOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue 3 2009DACVIM, Julia E. Cummings DVM Abstract Objective , To review zinc physiology and pathophysiology and the importance of zinc toxicity and deficiency in veterinary patients. Data Sources , A review of human and veterinary medical literature. Human Data Synthesis , There is a significant amount of original research in humans and animals on the role of zinc in multiple organ systems. There is also significant data available on human patients with zinc abnormalities. Veterinary Data Synthesis , Zinc deficiency has been studied in dogs with genetic disease and dietary deficiency leading to dermatological disease and immune deficiency. Zinc toxicity has been described after ingestion of metallic foreign bodies containing zinc. Conclusions , Historically, the role of zinc in health and disease has been studied through patients with toxicity or severe deficiency with obvious clinical signs. As the ubiquitous contribution of zinc to structure and function in biological systems was discovered, clinically significant but subtle deficiency states have been revealed. In human medicine, mild zinc deficiencies are currently thought to cause chronic metabolic derangement leading to or exacerbating immune deficiency, gastrointestinal problems, endocrine disorders, neurologic dysfunction, cancer, accelerated aging, degenerative disease, and more. Determining the causal relationships between mild zinc deficiency and concurrent disease is complicated by the lack of sensitive or specific tests for zinc deficiency. The prevalence of zinc deficiency and its contribution to disease in veterinary patients is not well known. Continued research is warranted to develop more sensitive and specific tests to assess zinc status, to determine which patients are at risk for deficiency, and to optimize supplementation in health and disease. [source] Corruption, Productivity and SocialismKYKLOS INTERNATIONAL REVIEW OF SOCIAL SCIENCES, Issue 2 2003Geoffrey Wyatt Summary The level of productivity is correlated across countries with measures of (lack of) corruption, but this appears to be due to a common association of these variables with measures of civil infrastructure, here measured by a combination of governance indexes labelled ,rule of law' and ,government effectiveness'. New instruments based on the size- and spatial-distributions of cities within the countries of the world were constructed in order to explore the causal relationships between civil infrastructure and productivity. Civil infrastructure accounts for a substantial fraction of the global variation in output per worker across countries. Within this empirical pattern there is a systematic deviation associated with the current and former socialist states, which have both lower productivity and inferior civil infrastructure than would be predicted for otherwise similar non-socialist states. However, for a given level of the index of civil infrastructure these states are also shown to have a higher level of productivity than otherwise similar non-socialist states. The unconditionally low productivity of socialist states is attributed entirely to the indirectly deleterious effects that socialism had on civil infrastructure, which more than offset its directly positive effect on output. [source] Below the tip of the iceberg: the co-evolution of formal and informal interorganizational relations in the wireless telecommunications industryMANAGERIAL AND DECISION ECONOMICS, Issue 5 2008Lori Rosenkopf We examine how alliances,formal, contractual interorganizational relations,co-evolve with emergent, informal interorganizational relations. To form alliances, firms must acquire information on potential partners, and the acquisition of this intelligence occurs through both formal and informal channels. Here we evaluate the effects of two of these informal channels: joint participation in cooperative technical organizations (CTOs) and director interlocks. Since director interlocks connect firms through the highest managerial levels while joint CTO participation connects firms through mid-level technical personnel, we examine whether each type of informal tie contributes to alliance formation as well as whether ties at multiple levels serve as complements or substitutes for this purpose. We also examine whether all types of ties,alliances, interlocks and CTO participation,co-evolve endogenously or whether there are more direct causal relationships between and among these various types of networks. We find that both interlocks and CTO participation facilitate alliance formation, yet interlocks only facilitate alliance formation when the common director serves as an officer in one of the firms. An additional distinction between the role of interlocks and CTO participation is that the relationship between interlocks and alliance formation appears endogenous, in contrast to CTO participation, which causally precedes alliance formation. Copyright © 2008 John Wiley & Sons, Ltd. [source] A METHOD FOR SIMPLIFYING LARGE ECOSYSTEM MODELSNATURAL RESOURCE MODELING, Issue 2 2008JOCK LAWRIE Abstract Simplifying large ecosystem models is essential if we are to understand the underlying causes of observed behaviors. However, such understanding is often employed to achieve simplification. This paper introduces two model simplification methods that can be applied without requiring intimate prior knowledge of the system. Their utility is measured by the resulting values of given model diagnostics relative to those of the large model. The first method is a simple automated procedure for nondimensionalizing large ecosystem models, which identifies and eliminates terms that have little effect on model diagnostics. Some of its limitations are then addressed by the rate elimination method, which measures the relative importance of model terms using least-squares regression. The methods are applied to a model of the nitrogen cycle in Port Phillip Bay, Victoria, Australia. The rate elimination method provided more insights into the causal relationships built into the model than the nondimensionalizing method. It also allowed the reduction of the model's dimension. Thus it is a useful first step in model simplification. [source] Utility of Noninvasive, Mobile, Continuous Outpatient Rhythm Monitoring to Diagnose Seizure-Related ArrhythmiasPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 7 2009KEVIN DRIVER M.D. The identification of patients with a diagnosis of seizure disorder who are also at risk for clinically significant bradycardia and/or tachycardia may require long-term cardiac rhythm monitoring. Noninvasive, continuous, outpatient cardiac rhythm monitoring may be useful for such clinical scenarios. The study group consisted of two male patients with a history of seizure disorder involving loss of consciousness. Clinical data and results of electrocardiography, echocardiography, electroencephelography, and continuous, mobile, outpatient cardiac rhythm monitoring are described. In the first patient, while cardiac bradyarrhythmias were secondary to seizures, sinus arrest most likely complicated the episodes by leading to more prolonged states of unconsciousness. In the second patient, permanent pacemaker implantation for AV block averted all clinical events previously attributed to seizures. Despite the different causal relationships between seizures and bradyarrhythmias in these two patients, mobile, cardiac outpatient telemetry was successful in diagnosing the contribution of cardiac dysrhythmia, leading to permanent pacemaker implantation. A diagnostic strategy that incorporates mobile, noninvasive, continuous, outpatient cardiac rhythm monitoring can effectively be utilized to diagnose significant seizure-related arrhythmias. [source] Rock and a Hard Place: Public Willingness to Trade Civil Rights and Liberties for Greater SecurityPOLITICS & POLICY, Issue 5 2009HANK C. JENKINS-SMITH Our research examines the implications of political beliefs for the relationship between preferences for freedom and security. We briefly situate the relationship in historical context and relate it to today's struggle with terrorism. Then we examine the influence of political beliefs on normative preferences for how liberty and security should be related and for perceptions of how they currently are being balanced. Using original data from a national Internet survey of more than 3,000 respondents, we examine causal relationships among core, domain, and policy context beliefs for preferences about balancing freedom and security. [source] INFRASTRUCTURE, LONG-RUN ECONOMIC GROWTH AND CAUSALITY TESTS FOR COINTEGRATED PANELSTHE MANCHESTER SCHOOL, Issue 5 2008DAVID CANNING We investigate the consequences of various types of infrastructure provision in a panel of countries from 1950 to 1992. We develop new tests which enable us to isolate the sign and direction of long-run effects in a manner that is robust to the presence of unknown heterogeneous short-run causal relationships. We show that while infrastructure does tend to cause long-run economic growth, there is substantial variation across countries. We also provide evidence that each infrastructure type is provided at close to the growth-maximizing level on average globally, but is under-supplied in some countries and over-supplied in others. [source] | |||||||||||||||||||||||||||||||||||||