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Conditional
Terms modified by Conditional Selected AbstractsMarket Response to Earnings Surprises Conditional on Reasons for an Auditor Change,CONTEMPORARY ACCOUNTING RESEARCH, Issue 2 2002Karl E. Hackenbrack Abstract Our interest in this study is the relative informativeness of earnings announcements reported before and after Form 8-K disclosures of the reason for an auditor change. We appeal to several models that predict that the market's response to an earnings surprise is positively related to the perceived precision of the earnings report. We predict that the Form 8-K reason disclosures aid investors in updating their expectations of earnings precision by providing useful information about the financial reporting process that produces the earnings report. For 802 auditor changes from late 1991 through late 1997, the average price response per unit of earnings surprise is lower subsequent to an auditor change for companies that switched for disagreement-related or fee-related reasons and higher for those that switched for service-related reasons. This paper provides further evidence on the effects of differential earnings quality on differences in the returns-earnings relation across companies and over time as well as the efficacy of Form 8-K disclosures of reasons for auditor changes. [source] Analysis of determinants of mammalian species richness in South America using spatial autoregressive modelsECOGRAPHY, Issue 4 2004Marcelo F. Tognelli Classically, hypotheses concerning the distribution of species have been explored by evaluating the relationship between species richness and environmental variables using ordinary least squares (OLS) regression. However, environmental and ecological data generally show spatial autocorrelation, thus violating the assumption of independently distributed errors. When spatial autocorrelation exists, an alternative is to use autoregressive models that assume spatially autocorrelated errors. We examined the relationship between mammalian species richness in South America and environmental variables, thereby evaluating the relative importance of four competing hypotheses to explain mammalian species richness. Additionally, we compared the results of ordinary least squares (OLS) regression and spatial autoregressive models using Conditional and Simultaneous Autoregressive (CAR and SAR, respectively) models. Variables associated with productivity were the most important at determining mammalian species richness at the scale analyzed. Whereas OLS residuals between species richness and environmental variables were strongly autocorrelated, those from autoregressive models showed less spatial autocorrelation, particularly the SAR model, indicating its suitability for these data. Autoregressive models also fit the data better than the OLS model (increasing R2 by 5,14%), and the relative importance of the explanatory variables shifted under CAR and SAR models. These analyses underscore the importance of controlling for spatial autocorrelation in biogeographical studies. [source] Ratings Changes, Ratings Levels, and the Predictive Value of Analysts' RecommendationsFINANCIAL MANAGEMENT, Issue 2 2010Brad M. Barber We show that abnormal returns to analysts' recommendations stem from both the ratings levels assigned and the changes in those ratings. Conditional on the ratings change, buy and strong buy recommendations have greater returns than do holds, sells, and strong sells. Conditional on the ratings level, upgrades earn the highest returns and downgrades the lowest. We also find that both ratings levels and changes predict future unexpected earnings and the associated market reaction. Our results imply that 1) investment returns may be enhanced by conditioning on both recommendation levels and changes; 2) the predictive power of analysts' recommendations reflects, at least partially, analysts' ability to generate valuable private information; and 3) some inconsistency exists between analysts' ratings and the formal ratings definitions issued by securities firms. [source] Premarital Living Arrangements and the Transition to First Marriage in JapanJOURNAL OF MARRIAGE AND FAMILY, Issue 2 2003James M. Raymo This article evaluates the relevance of a popular emphasis on the benefits of extended coresidence with parents as an explanation for the trend toward later marriage in Japan. Estimating hazard models for the transition to first marriage separately by gender, living arrangements, and birth cohort, I find that the trend toward later marriage is indeed more pronounced among young men and women living with parents. Conditional on coresidence, however, there is little evidence that access to parental provision of financial resources and domestic services is negatively associated with marriage. I suggest alternative scenarios in which parental resources may contribute to later marriage by facilitating children's independence rather than by keeping them at home. [source] The analysis of change, Newton's law of gravity and association modelsJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES A (STATISTICS IN SOCIETY), Issue 1 2008Mark de Rooij Summary., Newton's law of gravity states that the force between two objects in the universe is equal to the product of the masses of the two objects divided by the square of the distance between the two objects. In the first part of the paper it is shown that a model with a ,law-of-gravity' interpretation applies well to the analysis of longitudinal categorical data where the number of people changing their behaviour or choice from one category to another is a measure of force and the goal is to obtain estimates of mass for the two categories and an estimate of the distance between them. To provide a better description of the data dynamic masses and dynamic positions are introduced. It is shown that this generalized law of gravity is equivalent to Goodman's RC(M) association model. In the second part of the paper the model is generalized to two kinds of three-way data. The first case is when there are multiple two-way tables and in the second case we have change over three points of time. Conditional and partial association models are related to three-way distance models, like the INDSCAL model, and triadic distance models respectively. [source] GA2LEN skin test study III: Minimum battery of test inhalent allergens needed in epidemiological studies in patientsALLERGY, Issue 11 2009P.-J. Bousquet Background:, The number of allergens to be tested in order to identify sensitized patients is important in order to have the most cost-effective approach in epidemiological studies. Objective:, To define the minimal number and the type of skin prick test (SPT) allergens required to identify a patient as sensitized using results of the new Pan-European GA2LEN skin prick test study. Method:, In a large Pan-European multicenter (17 centers in 14 countries) patient based study, a standardized panel of 18 allergens has been prick tested using a standardized procedure. Conditional approach allowed to determine the allergens selection. Result:, Among the 3034 patients involved, 1996 (68.2%) were sensitized to at least one allergen. Overall, eight allergens (grass pollen, Dermatophagoides pteronyssinus, birch pollen, cat dander, Artemisia, olive pollen, Blatella and Alternaria) allowed to identified more than 95% of sensitized subjects. However, differences were observed between countries, two allergens being sufficient for Switzerland (grass pollen and cat dander) as opposed to nine for France (grass pollen, Dermatophagoides pteronyssinus, olive pollen, cat dander, Blatella, cypress, dog dander, alder and [Artemisia or Alternaria]). According to country, up to 13 allergens were needed to identify all sensitized subjects. Conclusion:, Eight to ten allergens allowed the identification of the majority of sensitized subjects. For clinical care of individual patients, the whole battery of 18 allergens is needed to appropriately assess sensitization across Europe. [source] A dynamic programming algorithm for the conditional covering problem on tree graphsNETWORKS: AN INTERNATIONAL JOURNAL, Issue 4 2005Jennifer A. Horne Abstract In a previous article, we presented algorithms for solving the Conditional Covering Problem (CCP) on path and extended star graphs. The CCP on these graphs can be solved in O(n2) time, where n is the number of nodes in the graph. In this article, we propose a new dynamic programming procedure to solve the CCP on tree graphs. This recursion works from the leaf nodes of the tree up to the root node, using notions of protected and unprotected costs as done for the CCP path algorithm in our previous work. We introduce new preliminary routines and data structures to merge information from subpaths and subtrees, resulting in an O(n4) algorithm to optimally solve the problem. © 2005 Wiley Periodicals, Inc. NETWORKS, Vol. 46(4), 186,197 2005 [source] Entrepreneurship and Post-socialist Growth,OXFORD BULLETIN OF ECONOMICS & STATISTICS, Issue 1 2005Daniel Berkowitz Abstract We use a rich regional data set to obtain a statistical characterization of the relationship between entrepreneurial activity and economic growth within post-Soviet Russia. Russia is a useful laboratory for evaluating links between entrepreneurial activity and growth because of the striking variation in initial conditions, the adoption of policy reforms, and entrepreneurial activity observed across its large number of regions in the early stages of transition. Russia has also experienced striking regional variation in subsequent growth. Conditional on variations in initial conditions and policy reform measures, regional entrepreneurial activity exhibits a statistically and quantitatively significant relationship with subsequent economic growth. [source] Equilibrium in a Dynamic Limit Order MarketTHE JOURNAL OF FINANCE, Issue 5 2005RONALD L. GOETTLER ABSTRACT We model a dynamic limit order market as a stochastic sequential game with rational traders. Since the model is analytically intractable, we provide an algorithm based on Pakes and McGuire (2001) to find a stationary Markov-perfect equilibrium. We then generate artificial time series and perform comparative dynamics. Conditional on a transaction, the midpoint of the quoted prices is not a good proxy for the true value. Further, transaction costs paid by market order submitters are negative on average, and negatively correlated with the effective spread. Reducing the tick size is not Pareto improving but increases total investor surplus. [source] THE ROLE OF SUNK COSTS IN THE DECISION TO INVEST IN R&D,THE JOURNAL OF INDUSTRIAL ECONOMICS, Issue 4 2009JUAN A. MÁÑEZ We present a dynamic empirical model of a firm's R&D decisions that is consistent with the existence of sunk R&D costs, taking into account that these costs may differ between small and large firms, and among different technological regimes. We estimate a multivariate dynamic discrete choice model using firm-level data of Spanish manufacturing for 1990,2000. Conditional on firm heterogeneity and serially correlated unobservable factors, we find that R&D history matters. This true state dependence allows inferring the existence of sunk R&D costs associated with performing R&D. Sunk R&D costs are found to be higher for large, high-tech firms. [source] A Non-parametric Conditional Bivariate Reference Region with an Application to Height/Weight Measurements on Normal GirlsBIOMETRICAL JOURNAL, Issue 4 2009Jorgen Holm Petersen Abstract A conceptually simple two-dimensional conditional reference curve is described. The curve gives a decision basis for determining whether a bivariate response from an individual is "normal" or "abnormal" when taking into account that a third (conditioning) variable may influence the bivariate response. The reference curve is not only characterized analytically but also by geometric properties that are easily communicated to medical doctors , the users of such curves. The reference curve estimator is completely non-parametric, so no distributional assumptions are needed about the two-dimensional response. An example that will serve to motivate and illustrate the reference is the study of the height/weight distribution of 7,8-year-old Danish school girls born in 1930, 1950, or 1970. [source] Conditional and Unconditional Simulation of Healthy Patients' Visual FieldsBIOMETRICAL JOURNAL, Issue 4 2004M. V. Ibáñez Abstract This paper describes a simulation problem, motivated by the study of glaucoma, a very serious and widespread ocular illness. To ascertain whether a patient suffers from glaucoma, a perimetric test is done, but the evolution of the disease is very slow, and large longitudinal sets of tests taken on the same patient are needed to study its evolution, to analyze the efficiency of existing methods to detect the progression of glaucoma and to develop new ones. Simulation can be a very useful procedure to get appropriate data sets to work with. Our aim in this work is to simulate several VFs in a healthy patient to reflect his evolution in time. We use a spatio-temporal model to simulate from, taking into account the correlation existing between the observed (or simulated) values in space and time. Two different simulation procedures (unconditional and conditional) are studied, and applied to obtain the simulations we are interested in. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Sensitivity Analyses Comparing Outcomes Only Existing in a Subset Selected Post-Randomization, Conditional on Covariates, with Application to HIV Vaccine TrialsBIOMETRICS, Issue 2 2006Bryan E. Shepherd Summary In many experiments, researchers would like to compare between treatments and outcome that only exists in a subset of participants selected after randomization. For example, in preventive HIV vaccine efficacy trials it is of interest to determine whether randomization to vaccine causes lower HIV viral load, a quantity that only exists in participants who acquire HIV. To make a causal comparison and account for potential selection bias we propose a sensitivity analysis following the principal stratification framework set forth by Frangakis and Rubin (2002, Biometrics58, 21,29). Our goal is to assess the average causal effect of treatment assignment on viral load at a given baseline covariate level in the always infected principal stratum (those who would have been infected whether they had been assigned to vaccine or placebo). We assume stable unit treatment values (SUTVA), randomization, and that subjects randomized to the vaccine arm who became infected would also have become infected if randomized to the placebo arm (monotonicity). It is not known which of those subjects infected in the placebo arm are in the always infected principal stratum, but this can be modeled conditional on covariates, the observed viral load, and a specified sensitivity parameter. Under parametric regression models for viral load, we obtain maximum likelihood estimates of the average causal effect conditional on covariates and the sensitivity parameter. We apply our methods to the world's first phase III HIV vaccine trial. [source] Structural Model Updating and Health Monitoring with Incomplete Modal Data Using Gibbs SamplerCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 4 2006Jianye Ching It is based on the Gibbs sampler, a stochastic simulation method that decomposes the uncertain model parameters into three groups, so that the direct sampling from any one group is possible when conditional on the other groups and the incomplete modal data. This means that even if the number of uncertain parameters is large, the effective dimension for the Gibbs sampler is always three and so high-dimensional parameter spaces that are fatal to most sampling techniques are handled by the method, making it more practical for health monitoring of real structures. The approach also inherits the advantages of Bayesian techniques: it not only updates the optimal estimate of the structural parameters but also updates the associated uncertainties. The approach is illustrated by applying it to two examples of structural health monitoring problems, in which the goal is to detect and quantify any damage using incomplete modal data obtained from small-amplitude vibrations measured before and after a severe loading event, such as an earthquake or explosion. [source] Tests of a Deferred Tax Explanation of the Negative Association between the LIFO Reserve and Firm Value,CONTEMPORARY ACCOUNTING RESEARCH, Issue 1 2000DAN S. DHALIWAL Guenther and Trombley (1994) and Jennings, Simko, and Thompson (1996) document a negative association between a firm's last-in, first-out (LIFO) reserve and the market value of its equity. In this paper, we test a deferred tax explanation of this negative association. Specifically, we argue that investors, conditional on adjusting inventory to as-if first-in, first-out (FIFO), estimate a firm's future LIFO liquidation tax burden as its LIFO reserve multiplied by the appropriate corporate tax rate and include this tax-adjusted LIFO reserve in the valuation of a LIFO firm's net assets. On the basis of this argument, the tax-adjusted LIFO reserve is in effect an estimate of an off-balance-sheet deferred tax liability and, as a result, we predict a negative association between the tax-adjusted LIFO reserve and market value of equity. We test our deferred tax explanation by estimating a valuation model in which a firm's market value of equity is expressed as a function of the firm's assets, liabilities, deferred tax liability, and tax-adjusted LIFO reserve; the model is estimated separately in years preceding and following the reduction of tax rates mandated by the US Tax Reform Act of 1986. Test results provide strong support for the deferred tax explanation of the negative association between a firm's LIFO reserve and the market value of its equity. [source] TRIGGER-POINT MECHANISM AND CONDITIONAL COMMITMENT: IMPLICATIONS FOR ENTRY, COLLUSION, AND WELFARECONTEMPORARY ECONOMIC POLICY, Issue 2 2007LARRY D. QIU When fixed, sunk investment costs are high, firms may not have sufficient incentive to enter the market unless future entry is constrained. In this case, the government faces a dilemma between a full commitment and noncommitment of restricted future entry. A way out is to consider a commitment conditional on the realization of the uncertain parameters, such as the trigger-point mechanism (TPM) that sets conditions on current production level, excess capacity, and demand growth under which future entry will be allowed. This article shows that the TPM facilitates the incumbents' collusion but may improve social welfare under certain circumstances. (JEL L13, L43, L50, H10, H54) [source] Targeted cell-ablation in Xenopus embryos using the conditional, toxic viral protein M2(H37A)DEVELOPMENTAL DYNAMICS, Issue 8 2007Stuart J. Smith Abstract Harnessing toxic proteins to destroy selective cells in an embryo is an attractive method for exploring details of cell fate and cell,cell interdependency. However, no existing "suicide gene" system has proved suitable for aquatic vertebrates. We use the M2(H37A) toxic ion channel of the influenza-A virus to induce cell-ablations in Xenopus laevis. M2(H37A) RNA injected into blastomeres of early stage embryos causes death of their progeny by late-blastula stages. Moreover, M2(H37A) toxicity can be controlled using the M2 inhibitor rimantadine. We have tested the ablation system using transgenesis to target M2(H37A) expression to selected cells in the embryo. Using the myocardial MLC2 promoter, M2(H37A)-mediated cell death causes dramatic loss of cardiac structure and function by stage 39. With the LURP1 promoter, we induce cell-ablations of macrophages. These experiments demonstrate the effectiveness of M2(H37A)-ablation in Xenopus and its utility in monitoring the progression of developmental abnormalities during targeted cell death experiments. Developmental Dynamics 236:2159,2171, 2007. © 2007 Wiley-Liss, Inc. [source] COMT Val158Met moderation of cannabis-induced psychosis: a momentary assessment study of ,switching on' hallucinations in the flow of daily lifeACTA PSYCHIATRICA SCANDINAVICA, Issue 2 2009C. Henquet Objective:, A functional polymorphism in the catechol- o -methyltransferase gene (COMT Val158Met) may moderate the psychosis-inducing effects of cannabis. In order to extend this finding to dynamic effects in the flow of daily life, a momentary assessment study of psychotic symptoms in response to cannabis use was conducted. Method:, The experience sampling technique was used to collect data on cannabis use and occurrence of symptoms in daily life in patients with a psychotic disorder (n = 31) and healthy controls (n = 25). Results:, Carriers of the COMT Val158Met Val allele, but not subjects with the Met/Met genotype, showed an increase in hallucinations after cannabis exposure, conditional on prior evidence of psychometric psychosis liability. Conclusion:, The findings confirm that in people with psychometric evidence of psychosis liability, COMT Val158Met genotype moderates the association between cannabis and psychotic phenomena in the flow of daily life. [source] Spatial conditional discrimination learning in developing ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2005Kevin L. Brown Abstract The present study established an effective procedure for studying spatial conditional discrimination learning in juvenile rats using a T-maze. Wire mesh located on the floor of the maze as well as a second, identical T-maze apparatus served as conditional cues which signaled whether a left or a right response would be rewarded. In Experiment 1, conditional discrimination was evident on Postnatal Day (PND) 30 when mesh,+,maze or maze-alone were the conditional cues, but not when mesh-alone was the cue. Experiment 2 confirmed that mesh-alone was sufficiently salient to support learning of a simple (nonconditional) discrimination. Its failure to serve as a conditional cue in Experiment 1 does not reflect its general ineffectiveness as a stimulus. Experiment 3 confirmed that the learning shown in Experiment 1 was indeed conditional in nature by comparing performance on conditional versus nonconditional versions of the task. Experiment 4 showed that PND19 and PND23 pups also were capable of performing the task when maze,+,mesh was the cue; however, the findings indicate that PND19 subjects do not use a conditional strategy to learn this task. The findings suggest postnatal ontogeny of conditional discrimination learning and underscore the importance of conditional cue salience, and of identifying task strategies, in developmental studies of conditional discrimination learning. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 97,110, 2005. [source] Bayes nets and babies: infants' developing statistical reasoning abilities and their representation of causal knowledgeDEVELOPMENTAL SCIENCE, Issue 3 2007David M. Sobel A fundamental assumption of the causal graphical model framework is the Markov assumption, which posits that learners can discriminate between two events that are dependent because of a direct causal relation between them and two events that are independent conditional on the value of another event(s). Sobel and Kirkham (2006) demonstrated that 8-month-old infants registered conditional independence information among a sequence of events; infants responded according to the Markov assumption in such a way that was inconsistent with models that rely on simple calculations of associative strength. The present experiment extends these findings to younger infants, and demonstrates that such responses potentially develop during the second half of the first year of life. These data are discussed in terms of a developmental trajectory between associative mechanisms and causal graphical models as representations of infants' causal and statistical learning. [source] Methods to account for spatial autocorrelation in the analysis of species distributional data: a reviewECOGRAPHY, Issue 5 2007Carsten F. Dormann Species distributional or trait data based on range map (extent-of-occurrence) or atlas survey data often display spatial autocorrelation, i.e. locations close to each other exhibit more similar values than those further apart. If this pattern remains present in the residuals of a statistical model based on such data, one of the key assumptions of standard statistical analyses, that residuals are independent and identically distributed (i.i.d), is violated. The violation of the assumption of i.i.d. residuals may bias parameter estimates and can increase type I error rates (falsely rejecting the null hypothesis of no effect). While this is increasingly recognised by researchers analysing species distribution data, there is, to our knowledge, no comprehensive overview of the many available spatial statistical methods to take spatial autocorrelation into account in tests of statistical significance. Here, we describe six different statistical approaches to infer correlates of species' distributions, for both presence/absence (binary response) and species abundance data (poisson or normally distributed response), while accounting for spatial autocorrelation in model residuals: autocovariate regression; spatial eigenvector mapping; generalised least squares; (conditional and simultaneous) autoregressive models and generalised estimating equations. A comprehensive comparison of the relative merits of these methods is beyond the scope of this paper. To demonstrate each method's implementation, however, we undertook preliminary tests based on simulated data. These preliminary tests verified that most of the spatial modeling techniques we examined showed good type I error control and precise parameter estimates, at least when confronted with simplistic simulated data containing spatial autocorrelation in the errors. However, we found that for presence/absence data the results and conclusions were very variable between the different methods. This is likely due to the low information content of binary maps. Also, in contrast with previous studies, we found that autocovariate methods consistently underestimated the effects of environmental controls of species distributions. Given their widespread use, in particular for the modelling of species presence/absence data (e.g. climate envelope models), we argue that this warrants further study and caution in their use. To aid other ecologists in making use of the methods described, code to implement them in freely available software is provided in an electronic appendix. [source] Transfer of endophyte-origin defensive alkaloids from a grass to a hemiparasitic plantECOLOGY LETTERS, Issue 12 2005Päivi Lehtonen Abstract Plants growing in natural environments experience myriad interactions with a diverse assemblage of pathogens, parasites and mutualists. Many of these interactions involve symbiotic bacteria and fungi, but they also include macroparasitic plants. In this study, we investigated the interactions among a host grass (Lolium pratense, ex., Festuca pratensis), its symbiotic endophytic fungus (Neotyphodium uncinatum), a root hemiparasitic plant (Rhinanthus serotinus) of the host grass and a generalist herbivore (aphid Aulacorthum solani) of the hemiparasite. We demonstrate that the hemiparasitic plant acquires defending mycotoxins produced by the endophytic fungus living within their shared host grass. The uptake of defensive mycotoxins from the endophyte-infected host grass enhances the resistance of the hemiparasitic plant to the generalist aphid herbivore. Endophyte infection increases the performance of the hemiparasitic plant, but reduces the growth of the host grass. In other words, the mutualistic endophytic fungus becomes parasitic in the presence of the hemiparasitic plant. Our results suggest that the outcomes of grass,endophyte interactions are conditional on the complexity of community-level interactions; thus, the outcome of multispecies interactions may not be predictable from pair-wise combinations of species. [source] Decision Theory Applied to an Instrumental Variables ModelECONOMETRICA, Issue 3 2007Gary Chamberlain This paper applies some general concepts in decision theory to a simple instrumental variables model. There are two endogenous variables linked by a single structural equation; k of the exogenous variables are excluded from this structural equation and provide the instrumental variables (IV). The reduced-form distribution of the endogenous variables conditional on the exogenous variables corresponds to independent draws from a bivariate normal distribution with linear regression functions and a known covariance matrix. A canonical form of the model has parameter vector (,, ,, ,), where ,is the parameter of interest and is normalized to be a point on the unit circle. The reduced-form coefficients on the instrumental variables are split into a scalar parameter ,and a parameter vector ,, which is normalized to be a point on the (k,1)-dimensional unit sphere; ,measures the strength of the association between the endogenous variables and the instrumental variables, and ,is a measure of direction. A prior distribution is introduced for the IV model. The parameters ,, ,, and ,are treated as independent random variables. The distribution for ,is uniform on the unit circle; the distribution for ,is uniform on the unit sphere with dimension k-1. These choices arise from the solution of a minimax problem. The prior for ,is left general. It turns out that given any positive value for ,, the Bayes estimator of ,does not depend on ,; it equals the maximum-likelihood estimator. This Bayes estimator has constant risk; because it minimizes average risk with respect to a proper prior, it is minimax. The same general concepts are applied to obtain confidence intervals. The prior distribution is used in two ways. The first way is to integrate out the nuisance parameter ,in the IV model. This gives an integrated likelihood function with two scalar parameters, ,and ,. Inverting a likelihood ratio test, based on the integrated likelihood function, provides a confidence interval for ,. This lacks finite sample optimality, but invariance arguments show that the risk function depends only on ,and not on ,or ,. The second approach to confidence sets aims for finite sample optimality by setting up a loss function that trades off coverage against the length of the interval. The automatic uniform priors are used for ,and ,, but a prior is also needed for the scalar ,, and no guidance is offered on this choice. The Bayes rule is a highest posterior density set. Invariance arguments show that the risk function depends only on ,and not on ,or ,. The optimality result combines average risk and maximum risk. The confidence set minimizes the average,with respect to the prior distribution for ,,of the maximum risk, where the maximization is with respect to ,and ,. [source] Ticket to trade: Belgian labour and globalization before 19141ECONOMIC HISTORY REVIEW, Issue 2 2008MICHAEL HUBERMAN Standard trade theory, as invoked by political scientists and economists, would anticipate that workers in Belgium, a small Old World country, rich in labour relative to land, were in a good position to benefit from the wave of globalization before 1914. However, wage increases remained modest and ,labour' moved slowly towards adopting a free-trade position. Beginning in 1885, the Belgian labour party backed free trade, but its support was conditional on more and better social legislation. Belgian workers' wellbeing improved in the wave of globalization, but the vehicle was labour and social legislation and not rising wages. [source] Statistical analysis of temperature impact on daily hospital admissions: analysis of data from Udine, ItalyENVIRONMETRICS, Issue 1 2006Francesco Pauli Abstract This article is devoted to the analysis of the relationship between the health status of an urban population and meteorological variables. The analysis considers daily number of hospital admissions, not due to surgery, regarding the population resident in the Municipality of Udine, aged 75 and over. Hourly records on temperature, humidity, rain, atmospheric pressure, solar radiation, wind velocity and direction recorded at an observation site located near the center of Udine are considered. The study also considers hourly measures of pollutant concentrations collected by six monitoring stations. All data are relative to the summer periods of years 1995,2003. Generalized additive models (GAM) are used in which the response variable is the number of hospital admissions and is assumed to be distributed as a Poisson whose rate varies as a possibly non-linear function of the meteorological variables and variables allowing for calendar effects and pollutant concentrations. The subsequent part of the analysis explores the distribution of temperature conditional on the number of daily admissions through quantile regression. A non-linear (N-shaped) relationship between hospital admissions and temperature is estimated; temperature at 07:00 is selected as a covariate, revealing that nighttime temperature is more relevant than daytime. The quantile regression analysis points out, as expected, that the distribution of temperature on days with more admissions has higher q -quantiles with q near unity, while a clear-cut conclusion is not reached for q quantiles with q near 0. Copyright © 2005 John Wiley & Sons, Ltd. [source] Site scores and conditional biplots in canonical correspondence analysisENVIRONMETRICS, Issue 1 2004Jan Graffelman Abstract Canonical correspondence analysis is an important multivariate technique in community ecology. It produces an interesting biplot that summarizes the data matrices involved in the analysis. The method produces two sets of site scores that can be used in a biplot. One set concerns site scores that are weighted averages of the species scores (WA scores), and the other set represents site scores that are linear combinations of the environmental variables (LC scores). We show that the use of both sets of scores in a CCA biplot can be justified. The use of the WA scores leads to the best possible representation of the species data conditional on the representation of the weighted averages. Likewise, the LC scores lead to the best possible representation of the environmental variables, also conditional on the representation of the weighted averages and on the use of a Mahalanobis metric. The eigenvalues obtained in CCA indicate how well the species data are represented when LC scores are used. The quality of representation of the species data when WA scores are used can be computed from the CCA eigenvalues and the variances of the WA scores. Scalar products between WA scores and environmental variable vectors do not form a biplot of the environmental data. Theoretical results are illustrated with Australian data from freshwater ecology. Copyright © 2003 John Wiley & Sons, Ltd. [source] How Effective is Farmer Early Retirement Policy?EUROCHOICES, Issue 3 2008Quelle est l'efficacité de la politique de préretraite pour les agriculteurs? Summary How Effective is Farmer Early Retirement Policy? Financial support for EU farmers seeking early retirement is a discretionary element of CAP rural development policy and some EU member states, most notably France, Ireland and Greece have chosen to implement the measure. We explore whether the introduction of such schemes is likely to represent good value for money. We use data from Northern Ireland, a region with a relatively small-scale family-farm structure, where there have been periodic calls from farmer groups to introduce support for early retirement. We estimate the benefits that might arise from the introduction of such a scheme using FADN data and a separate survey of 350 farmers aged 50 to 65. We find that farm scale is a significant determinant of profit per hectare but that operator age is not. Benefits from releasing land through an early retirement scheme are conditional on such transfers bringing about significant farm expansion and changes in land use. Even when these conditions are satisfied, however, pensions payments of only about one-third the statutory maximum could be justified in a best-case scenario. Almost a quarter of all payments would incur deadweight losses, i.e., go to farmers who would be retiring anyway. Overall, the economic case for such a scheme is considered to be weak. Le soutien financier aux agriculteurs de l'Union européenne qui veulent prendre une retraite anticipée est un élément discrétionnaire de la politique de développement rural de la PAC et certains pays membres, en tout premier lieu la France, l'Irlande et la Grèce, ont choisi de mettre en place cette mesure. Nous recherchons si l'introduction de telles mesures serait intéressante par rapport au coût financier. L'analyse porte sur des données nord-irlandaises, région d'exploitations familiales de taille relativement petite dans laquelle les représentants agricoles ont régulièrement appeléà la mise en place de soutien pour la retraite anticipée. Nous estimons les avantages que pourrait procurer l'introduction de cette mesure à l'aide de données du RICA et d'une enquête indépendante portant sur 350 agriculteurs âgés de 50 à 65 ans. Nous trouvons que la taille de l'exploitation est un déterminant significatif du profit par hectare mais que l'âge de l'exploitant n'en est pas un. Les avantages de la mise à disposition de terres grâce à un programme de préretraite dépendent de la capacité de ces transferts à entraîner un accroissement notable de la taille des exploitations et des modifications de l'utilisation des terres. Cependant, même lorsque ces conditions sont remplies, seuls des paiements représentant un tiers du niveau maximum prévu dans le programme de préretraite pourraient se justifier dans un scénario optimal. Pratiquement un quart du total des paiements serait liéà des pertes de bien-être, c'est-à-dire que les bénéficiaires seraient des agriculteurs qui aurait pris leur retraite de toute façon. Globalement, l'intérêt économique d'un tel programme est considéré comme faible. Die finanzielle Unterstützung von Landwirten in der EU, die in den Vorruhestand gehen möchten, stellt in der Politik der GAP zur Entwicklung des ländlichen Raums ein diskretionäres Element dar; in einigen Mitgliedsstaaten wie z.B. Frankreich, Irland und Griechenland wird diese Maßnahme angeboten. Wir untersuchen, ob es möglicherweise finanziell sinnvoll wäre, solche Programme einzuführen. Dazu ziehen wir Daten aus Nordirland heran, einer Region mit relativ kleinen landwirtschaftlichen Familienbetrieben, in der sich Landwirte regelmäßig dafür aussprechen, Vorruhestandprogramme einzuführen. Wir schätzen den Nutzen, der sich aus der Einführung eines solchen Programms ergeben könnte, anhand von INLB-Daten und einer gesonderten Befragung von 350 Landwirten im Alter von 50 bis 65 Jahren. Wir stellen fest, dass es sich bei der Betriebsgröße , im Gegensatz zum Alter des Betreibers , um einen entscheidenden Faktor für die Höhe des Gewinns pro Hektar handelt. Ein Nutzen aus der Landübertragung aufgrund eines Vorruhestandprogramms beruht auf solchen Transfers, die eine bedeutsame Betriebserweiterung und veränderte Flächennutzung zur Folge haben. Selbst wenn diese Bedingungen erfüllt werden, könnten günstigstenfalls nur Rentenzahlungen in Höhe von etwa einem Drittel der gesetzlich verankerten Höchstsumme gerechtfertigt werden. Beinahe ein Viertel aller Zahlungen wäre mit Mitnahmeeffekten verbunden, d.h. Landwirten zukommen, die ohnehin den Ruhestand antreten würden. Aus ökonomischer Sicht muss ein solches Programm als schwach eingestuft werden. [source] Testing Conditional Asset Pricing Models Using a Markov Chain Monte Carlo ApproachEUROPEAN FINANCIAL MANAGEMENT, Issue 3 2008Manuel Ammann G12 Abstract We use Markov Chain Monte Carlo (MCMC) methods for the parameter estimation and the testing of conditional asset pricing models. In contrast to traditional approaches, it is truly conditional because the assumption that time variation in betas is driven by a set of conditioning variables is not necessary. Moreover, the approach has exact finite sample properties and accounts for errors-in-variables. Using S&P 500 panel data, we analyse the empirical performance of the CAPM and theFama and French (1993)three-factor model. We find that time-variation of betas in the CAPM and the time variation of the coefficients for the size factor (SMB) and the distress factor (HML) in the three-factor model improve the empirical performance. Therefore, our findings are consistent with time variation of firm-specific exposure to market risk, systematic credit risk and systematic size effects. However, a Bayesian model comparison trading off goodness of fit and model complexity indicates that the conditional CAPM performs best, followed by the conditional three-factor model, the unconditional CAPM, and the unconditional three-factor model. [source] Conditioning Information and European Bond Fund PerformanceEUROPEAN FINANCIAL MANAGEMENT, Issue 2 2003Florinda Silva G11; G12; G14 In this paper we evaluate the performance of European bond funds using unconditional and conditional models. As conditioning information we use variables that we find to be useful in predicting bond returns in the European market. The results show that, in general, bond funds are not able to outperform passive strategies. These findings are robust to whatever model (unconditional versus conditional and single versus multi-index) we use. The multi-index model seems to add some explanatory power in relation to the single-index model. Furthermore, when we incorporate the predetermined information variables, we can observe a slight tendency towards better performance. This evidence is consistent with previous studies on stock funds and comes in support of the argument that conditional models might allow for a better assessment of performance. However, our results suggest that the impact of additional risk factors seems to be greater than the impact of incorporating predetermined information variables. [source] T-cell-specific deletion of gp130 renders the highly susceptible IL-10-deficient mouse resistant to intestinal nematode infectionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2009Nicolas Fasnacht Abstract Gp130 is the common receptor of the IL-6 family of cytokines and is involved in many biological processes, including acute phase response, inflammation and immune reactions. To investigate the role of gp130 under inflammatory conditions, T-cell-specific conditional gp130 mice were first bred to the IL-10-deficient background and were then infected with the gastrointestinal nematode Trichuris muris. While IL-10,/, mice were highly susceptible to T. muris, developed a mixed Th1/Th17 response and displayed severe inflammation of the caecum, infection of mice with an additional T-cell-specific deletion of gp130 signalling completely reversed the phenotype. These mice showed an accelerated worm expulsion that was associated with the rapid generation of a strong Th2 immune response and a significant increase in Foxp3-expressing Treg. Therefore, gp130 signalling in T cells regulates a switch between proinflammatory and pathogenic Th1/Th17 cells and regulatory Th2/Treg in vivo. Taken together, the data demonstrate that gp130 signalling in T cells is a positive regulator of inflammatory processes, favouring the Th1/Th17 axis. 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