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251.
Claudia García Román Salmerón Gómez Catalina B. García 《Journal of Statistical Computation and Simulation》2019,89(2):211-231
Ridge regression is the alternative method to ordinary least squares, which is mostly applied when a multiple linear regression model presents a worrying degree of collinearity. A relevant topic in ridge regression is the selection of the ridge parameter, and different proposals have been presented in the scientific literature. Since the ridge estimator is biased, its estimation is normally based on the calculation of the mean square error (MSE) without considering (to the best of our knowledge) whether the proposed value for the ridge parameter really mitigates the collinearity. With this goal and different simulations, this paper proposes to estimate the ridge parameter from the determinant of the matrix of correlation of the data, which verifies that the variance inflation factor (VIF) is lower than the traditionally established threshold. The possible relation between the VIF and the determinant of the matrix of correlation is also analysed. Finally, the contribution is illustrated with three real examples. 相似文献
252.
Martín Yago Cutter Susan L. Li Zhenlong Emrich Christopher T. Mitchell Jerry T. 《Population and environment》2020,42(1):4-27
Population and Environment - After a disaster, there is an urgent need for information on population mobility. Our analysis examines the suitability of Twitter data for measuring post-disaster... 相似文献
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S. Bereg J. M. Díaz-Báñez D. Flores-Peñaloza S. Langerman P. Pérez-Lantero J. Urrutia 《Journal of Combinatorial Optimization》2016,31(3):1160-1173
A set of vertical bars planted on given points of a horizontal line defines a fence composed of the quadrilaterals bounded by successive bars. A set of bars in the plane, each having one endpoint at the origin, defines an umbrella composed of the triangles bounded by successive bars. Given a collection of bars, we study how to use them to build the fence or the umbrella of maximum total area. We present optimal algorithms for these constructions. The problems introduced in this paper are related to the Geometric Knapsack problems (Arkin et al. in Algorithmica 10:399–427, 1993) and the Rearrangement Inequality (Wayne in Scripta Math 12(2):164–169, 1946). 相似文献
256.
Wilson López López Claudia Pineda Marín Paul C. Sorum Etienne Mullet 《Social indicators research》2016,126(2):689-710
Colombian laypersons’ perspectives regarding actual and potential drug policies were examined. Adults (N = 395) aged 18–68 and living in Bogota were presented with 24 vignettes that were composed according to two within-subject orthogonal factor designs: (a) Demand for drugs in the country × Current government policy regarding soft and hard drugs (from “laissez faire” policy for all drugs to complete prohibition of all drugs) and (b) Information campaigns regarding the dangerousness of drugs × Current policy. Participants rated the level of acceptability of each policy. Seven different perspectives were identified that can be grouped into five broad views. The first one (50 % of participants) was called “radical constructionists” because participants considered that all policies were unacceptable. The second one (19 %) was called “cultural conservatives” because only one drug policy was considered fully acceptable: complete prohibition (although half of the members of this group were willing to allow soft drugs to be sold freely). The third one (14 %) was called “progressive prohibitionists” because the preferred policies in this group were either complete prohibition or complete regulation by the government. The fourth one (8 %) was called “free trade libertarians” because the dominant opinion was that the drug market should be free. The last one (5 %) was called “progressive advocates of legalization” because the preferred policy in this group was complete regulation of all substances. In most cases, the presence of information campaigns was highly valued. Methodological implications and implications for decision-makers are discussed. 相似文献
257.
Marisa Salanova Angel Arturo López-González Susana Llorens Mario del Líbano Ma Teófila Vicente-Herrero Matias Tomás-Salvá 《Work and stress》2016,30(3):228-242
This study tests the relationships between workaholism (i.e. working excessively and compulsively), sleep problems and cardiovascular risk in 537 employees from five Spanish hospitals. Four types of worker (i.e. workaholics, positive workers, compulsive workers and hard workers) were distinguished, and their health indicators were compared. The results showed that workaholics experienced significantly more sleep problems (i.e. morning tiredness, sleeping while driving and sleeping fewer hours both on weekdays and at weekends, with poorer quality), had higher relative risk scores, and consumed more caffeine and alcohol than the other patterns of worker (positive, compulsive and hard workers). Further analyses revealed that sleep problems fully mediated the relationship between workaholism (i.e. working excessively and compulsively) and cardiovascular risk. The study emphasizes the fact that being a workaholic might be a significant risk factor for having sleep problems and cardiovascular disease. 相似文献
258.
Roberto Fernández-Gago Laura Cabeza-García Mariano Nieto 《Review of Managerial Science》2016,10(1):85-104
This paper aims to contribute to the empirical evidence relating corporate social responsibility (CSR), board composition, and firm performance. Using a sample of Spanish listed firms included in the IBEX 35 over the period 2005–2010 the results show that the percentage of independent directors affect firm CSR activities, and that this effect is moderated by the resources available to the firm (measured by return on assets). Also, the CSR has a mediating role on the relation between the independence of the board of directors and firm value. These results hold for other board characteristics (board size and women as directors). 相似文献
259.
This literature review analyzes leading international business and management journals from 2000 to 2012 in order to explore the role of national culture in international business research. Through the analysis of the 265 selected articles, the study thematically maps the field and identifies research challenges and opportunities. It reflects on avenues for future research related to both thematic and methodological issues, among them: research focused on the impact of the home/host national culture on internationalization processes (as existing literature mainly focuses on cultural distance); the role to be played by new theoretical frameworks; and the need to consider cultural positions and cultural friction rather than traditional cultural distance when analyzing internationalization decisions. 相似文献
260.