排序方式: 共有27条查询结果,搜索用时 31 毫秒
11.
Rasmus Tangsgaard Varneskov 《商业与经济统计学杂志》2016,34(1):1-22
This article develops a general multivariate additive noise model for synchronized asset prices and provides a multivariate extension of the generalized flat-top realized kernel estimators, analyzed earlier by Varneskov (2014), to estimate its quadratic covariation. The additive noise model allows for α-mixing dependent exogenous noise, random sampling, and an endogenous noise component that encompasses synchronization errors, lead-lag relations, and diurnal heteroscedasticity. The various components may exhibit polynomially decaying autocovariances. In this setting, the class of estimators considered is consistent, asymptotically unbiased, and mixed Gaussian at the optimal rate of convergence, n1/4. A simple finite sample correction based on projections of symmetric matrices ensures positive definiteness without altering the asymptotic properties of the estimators. It, thereby, guarantees the existence of nonlinear transformations of the estimated covariance matrix such as correlations and realized betas, which inherit the asymptotic properties from the flat-top realized kernel estimators. An empirically motivated simulation study assesses the choice of sampling scheme and projection rule, and it shows that flat-top realized kernels have a desirable combination of robustness and efficiency relative to competing estimators. Last, an empirical analysis of signal detection and out-of-sample predictions for a portfolio of six stocks of varying size and liquidity illustrates the use and properties of the new estimators. 相似文献
12.
Recent research on human nonverbal vocalizations has led to considerable progress in our understanding of vocal communication of emotion. However, in contrast to studies of animal vocalizations, this research has focused mainly on the emotional interpretation of such signals. The repertoire of human nonverbal vocalizations as acoustic types, and the mapping between acoustic and emotional categories, thus remain underexplored. In a cross-linguistic naming task (Experiment 1), verbal categorization of 132 authentic (non-acted) human vocalizations by English-, Swedish- and Russian-speaking participants revealed the same major acoustic types: laugh, cry, scream, moan, and possibly roar and sigh. The association between call type and perceived emotion was systematic but non-redundant: listeners associated every call type with a limited, but in some cases relatively wide, range of emotions. The speed and consistency of naming the call type predicted the speed and consistency of inferring the caller’s emotion, suggesting that acoustic and emotional categorizations are closely related. However, participants preferred to name the call type before naming the emotion. Furthermore, nonverbal categorization of the same stimuli in a triad classification task (Experiment 2) was more compatible with classification by call type than by emotion, indicating the former’s greater perceptual salience. These results suggest that acoustic categorization may precede attribution of emotion, highlighting the need to distinguish between the overt form of nonverbal signals and their interpretation by the perceiver. Both within- and between-call acoustic variation can then be modeled explicitly, bringing research on human nonverbal vocalizations more in line with the work on animal communication. 相似文献
13.
The new PR of states: How nation branding practices affect the security function of public diplomacy
This paper investigates how the role of public relations practice in public diplomacy is undergoing a transformation as a consequence of the influence from nation branding. A case study of the Danish government's response to the so-called Cartoon Crisis illustrates how the threat from international terrorism to national security initially served as a catalyst for new public diplomacy initiatives. But as the initiatives were implemented within a framework of nation branding the focus on risk reduction became subjected to a marketing logic and a new focus on economic objectives took over. The paper points to a possible future status of public diplomacy under the influence of nation branding: Public diplomacy may maintain a function pertinent to national security but as this function is incapable of managing real risks it will only serve as auto-communication that legitimizes security policy towards a domestic audience. In the public diplomacy efforts towards transnational publics the link to national security will completely disappear whereby the public relations of states is transformed to the marketing of states. 相似文献
14.
Abstract. This paper considers the problem of mapping spatial variation of yield in a field using data from a yield monitoring system on a combine harvester. The unobserved yield is assumed to be a Gaussian random field and the yield monitoring system data is modelled as a convolution of the yield and an impulse response function. This results in an unusual spatial covariance structure (depending on the driving pattern of the combine harvester) for the yield monitoring system data. Parameters of the impulse response function and the spatial covariance function of the yield are estimated using maximum likelihood methods. The fitted model is assessed using certain empirical directional covariograms and the yield is finally predicted using the inferred statistical model. 相似文献
15.
Frdric Lavancier Arnaud Poinas Rasmus Waagepetersen 《Scandinavian Journal of Statistics》2021,48(1):87-107
Estimating function inference is indispensable for many common point process models where the joint intensities are tractable while the likelihood function is not. In this article, we establish asymptotic normality of estimating function estimators in a very general setting of nonstationary point processes. We then adapt this result to the case of nonstationary determinantal point processes, which are an important class of models for repulsive point patterns. In practice, often first‐ and second‐order estimating functions are used. For the latter, it is a common practice to omit contributions for pairs of points separated by a distance larger than some truncation distance, which is usually specified in an ad hoc manner. We suggest instead a data‐driven approach where the truncation distance is adapted automatically to the point process being fitted and where the approach integrates seamlessly with our asymptotic framework. The good performance of the adaptive approach is illustrated via simulation studies for non‐stationary determinantal point processes and by an application to a real dataset. 相似文献
16.
Rasmus Lentz Dale T. Mortensen 《Econometrica : journal of the Econometric Society》2008,76(6):1317-1373
Productivity differences across firms are large and persistent, but the evidence for worker reallocation as an important source of aggregate productivity growth is mixed. The purpose of this paper is to estimate the structure of an equilibrium model of growth through innovation designed to identify and quantify the role of resource reallocation in the growth process. The model is a version of the Schumpeterian theory of firm evolution and growth developed by Klette and Kortum (2004) extended to allow for firm heterogeneity. The data set is a panel of Danish firms that includes information on value added, employment, and wages. The model's fit is good. The estimated model implies that more productive firms in each cohort grow faster and consequently crowd out less productive firms in steady state. This selection effect accounts for 53% of aggregate growth in the estimated version of the model. 相似文献
17.
ABSTRACTIn this article, we explore China Mieville’s novel The City and the City as a literary experiment for analyzing the dynamics of public secrecy. We explore public secrets as an intrinsic part of organizational life and as a framework for paying attention to the politics of organizing. First, we focus on the novel’s invention and use of the verb ‘unseeing’ to bring out the embodied and sensuous aspects of public secrecy as part of organizational processes. Second we unfold how, although the content of public secrets may turn out to be less spectacular than expected, it is exactly their mundaneness which is key to their political importance. This is important because in an increasingly disorganized and uncertain world, secrecy proliferates and the visibility of secrecy is often a strategic move to justify certain hidden actions. 相似文献
18.
Rasmus Heltberg 《Development policy review : the journal of the Overseas Development Institute》2007,25(6):681-698
Social protection (income) support to households in the wake of major natural disasters is assuming a growing role for the World Bank, and major cash transfers in Turkey, Sri Lanka, the Maldives and Pakistan are reviewed in this article. Such support is usually best provided directly as cash to affected households; it complements other relief and reconstruction efforts, is demanded by client countries and has a positive impact on short‐term food security and long‐term recovery. It could be geared for greater impact and more efficient delivery in future by the use of a best‐practice toolkit and a right‐on‐time technical assistance facility, and its integration in emergency preparedness and capacity‐building for implementing agencies. 相似文献
19.
The traveling salesman problem (TSP) is well-known and many specially developed solution procedures have been constructed to solve particular variants of it. This paper considers several different variants of TSP. However, developing tailored solution procedures for each is impractical. These problems are non-deterministic polynomial-time hard (NP hard). Solving them using standard linear programming/mixed integer programming (LP/MIP) solvers has therefore only been regarded to be feasible for very small problems. A careful consideration of the problem formulation may facilitate efficient software utilization, and for real-world problems this can have a considerable impact. Problems that were previously regarded as large and unwieldy are now easily solvable using spreadsheets, thanks to the recent advancement in general optimization software. 相似文献
20.
Death rates for working-age men in European state socialist countries deviated from general improvements in survival observed
in the rest of Europe during the 20th century. The magnitude of structural labor force changes across countries correlates
with lagged increases in death rates for men in the working ages. This pattern is consistent with a hypothesis that hyper-development
of heavy industry and stagnation (even contraction) of the service sector created anomic conditions leading to unhealthy lifestyles
and self-destructive behavior among men moving from primary-sector to secondary-sector occupations. Occupational contrasts
within countries similarly show concentration of rising male death rates among blue collar workers. Collapse of state socialist
systems produced rapid corrections in labor force structure after 1990, again correlated with a fading of the state socialist
mortality syndrome in following decades. 相似文献