23 resultados para Impact of compositional constraints-on correlation and covariance
em Consorci de Serveis Universitaris de Catalunya (CSUC), Spain
Resumo:
Researchers have used stylized facts on asset prices and trading volumein stock markets (in particular, the mean reversion of asset returnsand the correlations between trading volume, price changes and pricelevels) to support theories where agents are not rational expected utilitymaximizers. This paper shows that this empirical evidence is in factconsistent with a standard infite horizon perfect information expectedutility economy where some agents face leverage constraints similar tothose found in todays financial markets. In addition, and in sharpcontrast to the theories above, we explain some qualitative differencesthat are observed in the price-volume relation on stock and on futuresmarkets. We consider a continuous-time economy where agents maximize theintegral of their discounted utility from consumption under both budgetand leverage con-straints. Building on the work by Vila and Zariphopoulou(1997), we find a closed form solution, up to a negative constant, for theequilibrium prices and demands in the region of the state space where theconstraint is non-binding. We show that, at the equilibrium, stock holdingsvolatility as well as its ratio to stock price volatility are increasingfunctions of the stock price and interpret this finding in terms of theprice-volume relation.
New developments of peace research: The impact of recent campaigns on disarmament and human security
Resumo:
The present text, based on previous work done by the authors on peace research (Grasa 1990 and 2010) and the disarmament campaigns linked to Human Security (Alcalde 2009 and 2010), has two objectives. First, to present a new agenda for peace research, based on the resolution/transformation of conflicts and the promotion of collective action in furtherance of human security and human development. Second, to focus specifically on collective action and on a positive reading of some of the campaigns that have taken place during the last decades in order to see how the experiences of such will affect the future agenda for peace research and action for peace.
Resumo:
Reductions in firing costs are often advocated as a way of increasingthe dynamism of labour markets in both developed and less developed countries. Evidence from Europe and the U.S. on the impact of firing costs has, however, been mixed. Moreover, legislative changes both in Europe and the U.S. have been limited. This paper, instead, examines the impact of the Colombian Labour Market Reform of 1990, which substantially reduced dismissal costs. I estimate the incidence of a reduction in firing costs on worker turnover by exploiting the temporal change in the Colombian labour legislation as well as the variability in coverage between formal and informal sector workers. Using a grouping estimator to control for common aggregate shocks and selection, I find that the exit hazard rates into and out of unemployment increased after the reform by over 1% for formal workers (covered by the legislation) relative to informal workers (uncovered). The increase of the hazards implies a net decrease in unemployment of a third of a percentage point, which accounts for about one quarter of the fall in unemployment during the period of study.
Resumo:
In this paper we analyse, using Monte Carlo simulation, the possible consequences of incorrect assumptions on the true structure of the random effects covariance matrix and the true correlation pattern of residuals, over the performance of an estimation method for nonlinear mixed models. The procedure under study is the well known linearization method due to Lindstrom and Bates (1990), implemented in the nlme library of S-Plus and R. Its performance is studied in terms of bias, mean square error (MSE), and true coverage of the associated asymptotic confidence intervals. Ignoring other criteria like the convenience of avoiding over parameterised models, it seems worst to erroneously assume some structure than do not assume any structure when this would be adequate.
Resumo:
We investigate whether the gender composition of teams affect theireconomic performance. We study a large business game, played in groups ofthree, where each group takes the role of a general manager. There are twoparallel competitions, one involving undergraduates and the other involvingMBAs. Our analysis shows that teams formed by three women aresignificantly outperformed by any other gender combination, both at theundergraduate and MBA levels. Looking across the performancedistribution, we find that for undergraduates, three women teams areoutperformed throughout, but by as much as 10pp at the bottom and by only1pp at the top. For MBAs, at the top, the best performing group is two menand one woman. The differences in performance are explained bydifferences in decision-making. We observe that three women teams are lessaggressive in their pricing strategies, invest less in R&D, and invest more insocial sustainability initiatives, than any other gender combination teams.Finally, we find support for the hypothesis that it is poor work dynamicsamong the three women teams that drives the results.
Resumo:
Many regional governments in developed countries design programs to improve the competitiveness of local firms. In this paper, we evaluate the effectiveness of public programs whose aim is to enhance the performance of firms located in Catalonia (Spain). We compare the performance of publicly subsidised companies (treated) with that of similar, but unsubsidised companies (non-treated). We use the Propensity Score Matching (PSM) methodology to construct a control group which, with respect to its observable characteristics, is as similar as possible to the treated group, and that allows us to identify firms which retain the same propensity to receive public subsidies. Once a valid comparison group has been established, we compare the respective performance of each firm. As a result, we find that recipient firms, on average, change their business practices, improve their performance, and increase their value added as a direct result of public subsidy programs.
Resumo:
The paper assesses the relationship between the use of alternative workplace practices (AWP) and job satisfaction. Using a unique employeremployee data set with rich information on both firm and employee characteristics we test whether there is a positive impact of AWPs on job satisfaction (motivation hypothesis) or it is negative (intensification hypothesis). We expand a growing empirical literature focusing on small and medium size firms from a southern European area. Our results show an overall positive effect, depending on the specific practice considered. We also obtain some sort of time-dependence with the effects turning from negative to positive once the practice has been implemented for some time. Keywords: Job satisfaction, work organization, unobserved heterogeneity.
Resumo:
Background: Different regions in a genome evolve at different rates depending on structural and functional constraints. Some genomic regions are highly conserved during metazoan evolution, while other regions may evolve rapidly, either in all species or in a lineage-specific manner. A strong or even moderate change in constraints in functional regions, for example in coding regions, can have significant evolutionary consequences. Results: Here we discuss a novel framework, 'BaseDiver', to classify groups of genes in humans based on the patterns of evolutionary constraints on polymorphic positions in their coding regions. Comparing the nucleotide-level divergence among mammals with the extent of deviation from the ancestral base in the human lineage, we identify patterns of evolutionary pressure on nonsynonymous base-positions in groups of genes belonging to the same functional category. Focussing on groups of genes in functional categories, we find that transcription factors contain a significant excess of nonsynonymous base-positions that are conserved in other mammals but changed in human, while immunity related genes harbour mutations at base-positions that evolve rapidly in all mammals including humans due to strong preference for advantageous alleles. Genes involved in olfaction also evolve rapidly in all mammals, and in humans this appears to be due to weak negative selection. Conclusion: While recent studies have identified genes under positive selection in humans, our approach identifies evolutionary constraints on Gene Ontology groups identifying changes in humans relative to some of the other mammals.
Resumo:
The aim of this paper is to analyse the impact of university knowledge and technology transfer activities on academic research output. Specifically, we study whether researchers with collaborative links with the private sector publish less than their peers without such links, once controlling for other sources of heterogeneity. We report findings from a longitudinal dataset on researchers from two engineering departments in the UK between 1985 until 2006. Our results indicate that researchers with industrial links publish significantly more than their peers. Academic productivity, though, is higher for low levels of industry involvement as compared to high levels.
Resumo:
In this paper I study the effects of a regional free trade agreement on the demand for skill.I start by documenting a series of facts to shed light on the determinants of a steep increasein the relative demand of skilled labor in a panel of Argentinean industrial firms covering thetrade liberalization period. First, this is not explained by labor reallocation across industriesor firms but by skill upgrading within firms. Second, exporters upgrade skill faster than nonexporters. Third, firms upgrading skill also upgrade technology. These findings are consistentwith a model where a reduction in trading partner s tariffs induces the most productive firms(exporters) to adopt skill-intensive production technologies. Indeed, I find that the reduction inBrazil s tariffs induces the most productive Argentinean firms to upgrade skill, while the leastproductive ones downgrade. One third of the increase in the relative demand for skill can beattributed to the reduction in Brazil s tariffs.
Resumo:
One of the principle aims of the Working Families' Tax Credit in the UK was to increase the participation of single mothers. The literature to date concludes there was approximately a five-percentage-point increase in employment of single mothers. The differences-in-differences methodology that is typically used compares single mother with single women without children. However, the characteristics of these groups are very different, and change over time in relative covariates are likely to violate the identifying assumption. We find that when we control for differential trends between women with and without children, the employment effect of the policy falls significantly. Moreover, the effect is borne solely by those working full-time (30 hours or more), while having no effect on inducing people into the labor market from inactivity. Looking closely at important covariates over time, we can see sizeable changes in the relative returns to employment between the treatment and control groups.
Resumo:
A qualitative study of the impact of electronic journals on the information behavior of academics at Catalan universities shows that academics now read more, and more widely. However, their reading is becoming more superficial; they are compelled to improve their discrimination skills in order to decide what to read in more depth. The electronic accessibility of journals means that academics now make fewer library visits. Web browsing and TOC e-mail alerts are replacing physical browsing, and searching is a very popular option for keeping up to date with developments. Internet search engines, especially Google and Google Scholar, are becoming important sources of information for academics. However, they face problems in managing their personal scientific information.
Resumo:
Many regional governments in developed countries design programs to improve the competitiveness of local firms. In this paper, we evaluate the effectiveness of public programs whose aim is to enhance the performance of firms located in Catalonia (Spain). We compare the performance of publicly subsidised companies (treated) with that of similar, but unsubsidised companies (non-treated). We use the Propensity Score Matching (PSM) methodology to construct a control group which, with respect to its observable characteristics, is as similar as possible to the treated group, and that allows us to identify firms which retain the same propensity to receive public subsidies. Once a valid comparison group has been established, we compare the respective performance of each firm. As a result, we find that recipient firms, on average, change their business practices, improve their performance, and increase their value added as a direct result of public subsidy programs.
Resumo:
With European Monetary Union (EMU), there was an increase in the adjusted spreads (corrected from the foreign exchange risk) of euro participating countries' sovereign securities over Germany and a decrease in those of non-euro countries. The objective of this paper is to study the reasons for this result, and in particular, whether the change in the price assigned by markets was due to domestic factors such as credit risk and/or market liquidity, or to international risk factors. The empirical evidence suggests that market size scale economies have increased since EMU for all European markets, so the effect of the various risk factors, even though it differs between euro and non-euro countries, is always dependent on the size of the market.
Resumo:
Many regional governments in developed countries design programs to improve the competitiveness of local firms. In this paper, we evaluate the effectiveness of public programs whose aim is to enhance the performance of firms located in Catalonia (Spain). We compare the performance of publicly subsidised companies (treated) with that of similar, but unsubsidised companies (non-treated). We use the Propensity Score Matching (PSM) methodology to construct a control group which, with respect to its observable characteristics, is as similar as possible to the treated group, and that allows us to identify firms which retain the same propensity to receive public subsidies. Once a valid comparison group has been established, we compare the respective performance of each firm. As a result, we find that recipient firms, on average, change their business practices, improve their performance, and increase their value added as a direct result of public subsidy programs.