Sentiment Composition Using a Parabolic Model

International audienceIn this paper, we propose a computational model that accounts for the effects of negation and modality on opinion expressions. Based on linguistic experiments informed by native speakers, we distil these effects according to the type of modality and negation. The model relies on a parabolic representation where an opinion expression is represented as a point on a parabola. Negation is modelled as functions over this parabola whereas modality through a family of parabolas of different slopes; each slope corresponds to a different certainty degree. The model is evaluated using two experiments, one involving direct strength judgements on a 7-point scale and the other relying on a sentiment annotated corpus. The empirical evaluation of our model shows that it matches the way humans handle negation and modality in opinionated sentence

Three-State Sentiment Dynamics

The main objective of this thesis is a detailed modeling of the dynamic components, i.e. transition rates with an embedded 'herding' component, in a stochastic framework. In addition to bold and cautious sentiment neutrality is incorporated into three versions of three-state models of sentiment dynamics. One version is formalized via the transition probability approach while a second version utilizes the discrete choice framework. The third model considers a bold opinion index and a neutrality index. Survey data on American investor sentiment is used to estimate the model parameters via maximum likelihood. The forecasting performance of this model is remarkable in terms of all three sentiments. The models exhibit a realistic description of the underlying group dynamics, including the separate treatment of the neutral agents. The findings provide an indication of the necessary degree of complexity of behavioral models in different scenarios. It can be concluded that the neutrality index adds additional explanatory power

Rational forecasts or social opinion dynamics? Identification of interaction effects in a business climate survey

This paper develops a methodology for estimating the parameters of dynamic opinion or expectation formation processes with social interactions. We study a simple stochastic framework of a collective process of opinion formation by a group of agents who face a binary decision problem. The aggregate dynamics of the individuals' decisions can be analyzed via the stochastic process governing the ensemble average of choices. Numerical approximations to the transient density for this ensemble average allow the evaluation of the likelihood function on the base of discrete observations of the social dynamics. This approach can be used to estimate the parameters of the opinion formation process from aggregate data on its average realization. Our application to a well-known business climate index provides strong indication of social interaction as an important element in respondents' assessment of the business climate. --Business climate,Business cycle forecasts,Opinion formation,Social interactions

Do private rental tenants pay for energy efficiency?: The dynamics of green premiums and brown discounts

The rental market, notably within the UK, is facing increased scrutiny with the tightening of regulation in relation to energy performance and the increases in energy costs and rental unaffordability. Whilst a sizeable volume of research has examined the pricing effects of EPCs and house prices, scrutiny of this relationship within the private rental sector remains more embryonic. This study, using 2,914 transactions for Northern Ireland, extends the traditional analysis beyond the conditional mean estimate by examining the quantiles of the relationship between EPCs and rental prices. The findings provide evidence of a rental premium of 0.2% for a one-point improvement in energy efficiency. In terms of EPC ratings, we find premiums for B- and C-rated dwellings of 8.2% and 2.4% and also discount effects for E, F and G-rated properties ranging between 3.9%-5.5%. The quantile findings exhibited a parabolic effect across the price distribution demonstrating the lowest and highest priced properties to comprise higher price premiums of 13% and 16% for B-rated dwellings, however more pronounced discount effects for F- and G-rated properties at the lowest and highest deciles. The findings provide evidence to help alleviate the split-incentive problem between landlords and tenants within the UK

THE EFFECTS OF DEMOGRAPHIC TRENDS ON ECONOMIC GROWTH IN THE EUROPEAN UNION

The aim of this article is to assess the influence of demographic age shares on changes in economic growth in the EU from 1996 to 2013 using a fixed effects model. The authors hypothesise the demographic variable having a statistically significant effect on the macroeconomic variable. Conclusions and suggestions stemming from the analysis are expected to benefit policymakers and provide guidance to public institutions

Turbulent Cells in Stars: I. Fluctuations in Kinetic Energy and Luminosity

Three-dimensional (3D) hydrodynamic simulations of shell oxygen burning (Meakin and Arnett, 2007b) exhibit bursty, recurrent fluctuations in turbulent kinetic energy. These are shown to be due to a general instability of the convective cell, requiring only a localized source of heating or cooling. Such fluctuations are shown to be suppressed in simulations of stellar evolution which use mixing-length theory (MLT). Quantitatively similar behavior occurs in the model of a convective roll (cell) of Lorenz (1963), which is known to have a strange attractor that gives rise to chaotic fluctuations in time of velocity and, as we show, luminosity. Study of simulations suggests that the behavior of a Lorenz convective roll may resemble that of a cell in convective flow. We examine some implications of this simplest approximation, and suggest paths for improvement. Using the Lorenz model as representative of a convective cell, a multiple-cell model of a convective layer gives total luminosity fluctuations which are suggestive of irregular variables (red giants and supergiants (Schwarzschild 1975)), and of the long secondary period feature in semi-regular AGB variables (Stothers 2010, Wood, Olivier and Kawaler 2004). This "tau-mechanism" is a new source for stellar variability, which is inherently non-linear (unseen in linear stability analysis), and one closely related to intermittency in turbulence. It was already implicit in the 3D global simulations of Woodward, Porter and Jacobs (2003). This fluctuating behavior is seen in extended 2D simulations of CNeOSi burning shells (Arnett and Meakin 2011b), and may cause instability which leads to eruptions in progenitors of core collapse supernovae PRIOR to collapse.Comment: 30 pages, 13 figure