Summary. We model daily catches of fishing boats in the Grand Bank fishing grounds. We use data on catches per species for a number of vessels collected by the European Union in the context of the Northwest Atlantic Fisheries Organization. Many variables can be thought to influence the amount caught: a number of ship characteristics (such as the size of the ship, the fishing technique used and the mesh size of the nets) are obvious candidates, but one can also consider the season or the actual location of the catch. Our database leads to 28 possible regressors (arising from six continuous variables and four categorical variables, whose 22 levels are treated separately), resulting in a set of 177 million possible linear regression models for the log-catch. Zero observations are modelled separately through a probit model. Inference is based on Bayesian model averaging, using a Markov chain Monte Carlo approach. Particular attention is paid to the prediction of catches for single and aggregated ships. 相似文献
This work develops a new methodology in order to discriminate models for interval- censored data based on bootstrap residual simulation by observing the deviance difference from one model in relation to another, according to Hinde (1992). Generally, this sort of data can generate a large number of tied observations and, in this case, survival time can be regarded as discrete. Therefore, the Cox proportional hazards model for grouped data (Prentice & Gloeckler, 1978) and the logistic model (Lawless, 1982) can be fitted by means of generalized linear models. Whitehead (1989) considered censoring to be an indicative variable with a binomial distribution and fitted the Cox proportional hazards model using complementary log-log as a link function. In addition, a logistic model can be fitted using logit as a link function. The proposed methodology arises as an alternative to the score tests developed by Colosimo et al. (2000), where such models can be obtained for discrete binary data as particular cases from the Aranda-Ordaz distribution asymmetric family. These tests are thus developed with a basis on link functions to generate such a fit. The example that motivates this study was the dataset from an experiment carried out on a flax cultivar planted on four substrata susceptible to the pathogen Fusarium oxysoprum . The response variable, which is the time until blighting, was observed in intervals during 52 days. The results were compared with the model fit and the AIC values. 相似文献
The author argues that despite the declaration for the end of ethnography by some North American scholars, ethnography is precisely what is needed for a more nuanced and complex understanding of cultural change. Using snippets of ethnographic observation from the Mexican state of Michoacan, the argument is made that neither "modernization" nor "globalization" are imposed from above, but are woven together with local processes to create institutions and practices which synthesize both the "traditional" and the "modern" in previously unimagined ways. Local people and processes are thus conceived of as dynamic partners in cultural change rather than passive subjects. Ethnography, then, is a fruitful means for uncovering how and the extent to which this is so. 相似文献
Urbanization is a major cause of biodiversity loss and disconnection between people and nature. For this reason, the creation and maintenance of green areas as part of the urban landscape is a common practice in cities around the world. These green areas are generally a result of particular public policies regarding how these areas can be accessed, maintained, and how they are connected to other natural fragments in the city. In an effort to investigate aspects of the ecology of such green areas of the city of Curitiba, southern Brazil, the present study measured distinct parameters of the structure of butterfly assemblages from 19 forest fragments of distinct classes of protection, testing the influence of different policies (protection category) on butterfly assemblages. Comparatively, we also tested the predictive power of landscape variables (at distinct scales) and fragment quality (e.g. diameter at breast height, density of vegetation) using Generalized Linear Models (GLMs). Overall, 14,596 individuals belonging to 412 butterfly species were recorded, but values of species diversity and composition are very heterogeneous, indicating that the protection categories do not significantly interfere with the structure of the butterfly assemblages. More important than the protection category is the forest fragment quality and landscape connectivity. Our models showed that degraded fragments tend to present a specific butterfly composition, whereas the more urbanized landscape have poor butterfly species richness. These results reinforce the importance of implementing public policies that prioritize the conservation of the quality of forest fragments in every class of protection, as well as the conservation of forest fragments throughout the urban landscape.
This paper addresses the role of negative asymmetries in emotional self-prediction by looking at the extent to which individuals misestimate their own betting behavior in sequential gambles. In a series of three experimental studies, we demonstrate that losses lead to higher than planned bets whereas bets are on average carried over after gains. Such asymmetric deviations from the plan emerge (1) when monetary and non-monetary incentives are used, and (2) when participants face fair and unfair gambles. The asymmetry is based on people’s inability to predict how much the negative emotions generated by a bad experience (e.g. the loss) will influence them to put more effort (e.g. bet more) than planned in an attempt to re-establish a homeostatic state in the prospect of a good experience (e.g. winning). 相似文献
Economic literature suggests that economic factors and the availability of amenities act as determinants of migration choices together with socio‐demographic factors. Migration has also been found to be the consequence of political instability. This article argues that specific political events, i.e., democratic elections, may be linked to migration flows. By using European data over the 1999‐2012 time period, our system GMM estimations reveal that there is an emigration political cycle across European democracies and across the young democracies of Central and Eastern European countries. We observe that regular elections tend to diminish emigration ratios, whereas endogenous elections have the opposite effect. These results suggest special challenges for governments and oppositions, which are also discussed. 相似文献
Ted Robert Gurr, Rogues, Rebels, and Reformers. A Political History of Urban Crime and Conflict (1977), xii+192 (Sage, Beverly Hills and London, £7.50) 相似文献
When studying associations between a functional covariate and scalar response using a functional linear model (FLM), scientific knowledge may indicate possible monotonicity of the unknown parameter curve. In this context, we propose an F-type test of monotonicity, based on a full versus reduced nested model structure, where the reduced model with monotonically constrained parameter curve is nested within an unconstrained FLM. For estimation under the unconstrained FLM, we consider two approaches: penalised least-squares and linear mixed model effects estimation. We use a smooth then monotonise approach to estimate the reduced model, within the null space of monotone parameter curves. A bootstrap procedure is used to simulate the null distribution of the test statistic. We present a simulation study of the power of the proposed test, and illustrate the test using data from a head and neck cancer study. 相似文献
In the study of risks, different sciences use the same category in different ways, each related to its own ontological assumptions. But many of
these fields communicate very little with one another. This article seeks to approximate two of these areas of study that
have shown similar concerns and that can mutually strengthen one another, namely, geography and demography. Geography was
one of the first disciplines to include risk in its environmental dimension and has had broad experience in simultaneously
focusing on social and natural dynamics. Demography, on the other hand, faces greater difficulties because only recently has
it incorporated the environmental dimension into its scientific scope. Both have brought the concept of vulnerability into
their conceptual framework as complementary to that of risk. Geographers understand vulnerability as a more symbiotic form
of the relationship between society and nature, whereas demographers give it a strong socioeconomic component. In this regard,
the conceptual discussion on risks and vulnerabilities, in its attempt at approximating these two fields, is a way of conceptually
advancing and strengthening the different approaches to empirical work, especially in population–environment studies which
is the common ground for the dialogue between the two disciplines.