Search results for "selection"
showing 10 items of 1940 documents
Embedding Evolution in Epidemic-Style Forwarding
2007
International audience; In this work, we introduce a framework to let forwarding schemes evolve in order to adapt to changing and a priori unknown environments. The framework is inspired by genetic algorithms: at each node a genotype describes the forwarding scheme used, a selection process fosters the diffusion of the fittest genotypes in the system and new genotypes are created by combining existing ones or applying random changes. A case study implementation is presented and its performance evaluated via numerical simulations.
School teachers bullied by their students: Teachers´ attributions and how they share their experiences
2012
Abstract Previous studies suggest that many teachers worldwide are bullied by students. However, deeper understanding of teachers' bullying experiences; of their interpretations of the causes of bullying; and of how they cope with these experiences, is lacking. Using an Internet survey we examined the attributions made by Finnish elementary and lower secondary school teachers for their victimisation; the people with whom they share their experiences; and the links between these. Three kinds of attribution were identified: student-related, institution-related, and teacher-related. Selection of the persons with whom teachers shared their experiences was determined by the nature of the attribu…
Assessment of wastewater treatment alternatives for small communities: An analytic network process approach
2015
The selection of the most appropriate wastewater treatment (WWT) technology is a complex problem since many alternatives are available and many criteria are involved in the decision-making process. To deal with this challenge, the analytic network process (ANP) is applied for the first time to rank a set of seven WWT technology set-ups for secondary treatment in small communities. A major advantage of ANP is that it incorporates interdependent relationships between elements. Results illustrated that extensive technologies, constructed wetlands and pond systems are the most preferred alternatives by WWT experts. The sensitivity analysis performed verified that the ranking of WWT alternatives…
Using active learning to adapt remote sensing image classifiers
2011
The validity of training samples collected in field campaigns is crucial for the success of land use classification models. However, such samples often suffer from a sample selection bias and do not represent the variability of spectra that can be encountered in the entire image. Therefore, to maximize classification performance, one must perform adaptation of the first model to the new data distribution. In this paper, we propose to perform adaptation by sampling new training examples in unknown areas of the image. Our goal is to select these pixels in an intelligent fashion that minimizes their number and maximizes their information content. Two strategies based on uncertainty and cluster…
On the value of drovers’ routes as environmental assets: A contingent valuation approach
2013
The aim of this study was to evaluate the non-market benefits resulting from the restoration of an old drovers’ route for recreation uses in Valencia (Spain). The valuation was carried out using the Contingent Valuation Method (CVM) through the elicitation of individuals’ willingness to pay (WTP). Since 52% of the respondents stated a zero WTP response, in order to inform decision-making processes more accurately, special attention was paid to the problem of zero and protest responses, and also to the possible presence of self-selection by those that protested. For the different specifications considered, results suggest that mean WTP estimates are higher for “rural areas” than for “the Val…
Willingness to pay to improve urban water supply: the case of Sucre, Bolivia
2014
In this study the contingent valuation method is applied in order to estimate the willingness to pay (WTP) of the inhabitants of Sucre (Bolivia) for an improvement in the urban water supply system. The study finds that about 55 per cent of households would be willing to pay an increase in their water bill for an improvement in the service. In order to deal with the problem of protest responses and the possible presence of a sample selection bias, a Heckman two-step model was estimated. More specifically, the econometric analysis undertaken reveals that there is no evidence of sample selection bias and that WTP positively relates to the respondents' household income, their level of education…
Informal employment in developing countries
2012
There is an ongoing debate among researchers and policy makers, whether informal sector employment is a result of competitive market forces or labor market segmentation. More recently it has been argued that none of the two theories sufficiently explains informal employment, but that the informal sector shows a heterogenous structure. For some workers the informal sector is an attractive employment opportunity, whereas for others – rationed out of the formal sector – the informal sector is a strategy of last resort. To test the empirical relevance of this hypothesis we formulate an econometric model which allows for several unobserved segments within the informal sector and apply it to the …
The consequences on job satisfaction of job–worker educational and skill mismatches in the Spanish labour market: a panel analysis
2012
The effects of job-worker mismatches on job satisfaction are examined using the eight waves (1994-2001) of Spanish data taken from the European Community Household Panel (ECHP). The impacts of both educational and skill mismatches are estimated considering unobserved heterogeneity, state dependence and attrition bias. Dynamic analysis shows that skill mismatches emerge as a much better predictor of job satisfaction than educational mismatches as the effects of the latter are related to unobserved heterogeneity among workers. Moreover, the current level of job satisfaction appears to be influenced by workers' previous job perceptions, suggesting a dynamic structure for job satisfaction.
Unemployment and Migration: Does Moving Help?
2002
Abstract The migration behaviour of the unemployed in Finland is analysed in terms of the causal effectof moving on individual employment status. In 1994, 17 percent of the labour force wasunemployed and the unemployment rate exhibited a very slow decline in 1994–1996. Overhalf of those who were unemployed at the end of 1994 were still unemployed two years later.The propensity to find a job is somewhat greater among migrants. However, the positive effectof moving diminishes once other personal characteristics are accounted for. Moreover, whencontrolling for endogenous migrant selectivity, an insignificant or even negative effect onemployment status emerges. This indicates that the relatively …
Effects of Grade Retention Policies: A Literature Review of Empirical Studies Applying Causal Inference
2021
The identification of the causal effects of grade retention policies is of enormous relevance for researchers and policymakers alike. Taking advantage of the availability of more detailed longitudinal datasets, researchers have been able to apply different identification strategies that address the classical problems of selection bias and unobserved heterogeneity that have plagued previous studies on the effect of retention. We present a systematic literature review of empirical studies aiming to unveil the causal effects of retention. This study underlines the need to consider and evaluate different kinds of grade retention polices as their effects vary depending on several dimensions (suc…