How Important is Syntactic Parsing Accuracy? An Empirical Evaluation on Rule-Based Sentiment Analysis

Syntactic parsing, the process of obtaining the internal structure of sentences in natural languages, is a crucial task for artificial intelligence applications that need to extract meaning from natural language text or speech. Sentiment analysis is one example of application for which parsing has recently proven useful. In recent years, there have been significant advances in the accuracy of parsing algorithms. In this article, we perform an empirical, task-oriented evaluation to determine how parsing accuracy influences the performance of a state-of-the-art rule-based sentiment analysis system that determines the polarity of sentences from their parse trees. In particular, we evaluate the system using four well-known dependency parsers, including both current models with state-of-the-art accuracy and more innacurate models which, however, require less computational resources. The experiments show that all of the parsers produce similarly good results in the sentiment analysis task, without their accuracy having any relevant influence on the results. Since parsing is currently a task with a relatively high computational cost that varies strongly between algorithms, this suggests that sentiment analysis researchers and users should prioritize speed over accuracy when choosing a parser; and parsing researchers should investigate models that improve speed further, even at some cost to accuracy.Comment: 19 pages. Accepted for publication in Artificial Intelligence Review. This update only adds the DOI link to comply with journal's term

The Determinants of Institutional Quality. More on the Debate

This paper provides new evidences about the determinants of institutional quality. Given the shortcomings of governance indicators, we first discuss the criteria employed to judge institutional quality. Then, we identify the factors that, according to these criteria, shape the quality of institutions. The results of this empirical research show that the main determinants of the quality of the institutions of a given country are its income per head and its income distribution, the efficiency of its tax system and the educational level of its population. Interestingly, some of the variables identified in previous literature (location, ethnolinguistic fragmentation, the origin of the legal system or colonial origin) either do not have any impact on institutional quality or they impact indirectly through the variables previously mentioned.Institutional Quality Development, Income Distribution, Tax System

One model, two languages: training bilingual parsers with harmonized treebanks

We introduce an approach to train lexicalized parsers using bilingual corpora obtained by merging harmonized treebanks of different languages, producing parsers that can analyze sentences in either of the learned languages, or even sentences that mix both. We test the approach on the Universal Dependency Treebanks, training with MaltParser and MaltOptimizer. The results show that these bilingual parsers are more than competitive, as most combinations not only preserve accuracy, but some even achieve significant improvements over the corresponding monolingual parsers. Preliminary experiments also show the approach to be promising on texts with code-switching and when more languages are added.Comment: 7 pages, 4 tables, 1 figur

Miradas torcidas. Percepciones mutuas entre España y Estados Unidos

La opción que tomó el gobierno español al alinearse con Estados Unidos en la invasión de Irak le ha llevado a actuar en contra de la opinión de más del 80% de los españoles. Como veremos, este comportamiento inhabitual hunde sus raíces en la acusada disparidad de valoraciones sobre la política exterior de la administración Bush que existe en España. Mientras una minoría de españoles, en la que se incluye el presidente Aznar y su gobierno, la defienden, la gran mayoría de los españoles la rechazan. La guerra de Irak ya ha pasado, pero está en curso una postguerra caótica y cruenta que va para largo. España deberá continuar manteniendo relaciones con Estados Unidos y la cuestión es si lo hará prolongando el profundo desencuentro entre gobierno y opinión pública surgido en los primeros meses de 2003. Ésta es la cuestión que motiva el presente trabajo, aunque no entraré a analizar la política de uno y otro gobierno ni a especular sobre sus posibles cambios. Las páginas que siguen están centradas en la tercera variable, las percepciones entre españoles y estadounidenses. Una variable que, si no de inmediato, a más largo plazo dejará sentir su influencia en la actitud del gobierno español. En este trabajo comenzaré recuperando las conclusiones cualitativas de un análisis sobre percepciones entre españoles y estadounidenses que llevé a cabo años atrás, para después contrastar esas conclusiones con los datos que a este respecto ofrecen una serie de estudios cuantitativos recientes. Esto mostrará su vigencia u obsolescencia y ofrecerá indicaciones sobre el grado de realismo de cualquier política que para asentarse sólidamente requiera un cambio profundo en las percepciones entre españoles y estadounidenses

Velocity dispersion estimates of APM galaxy clusters

We present 83 new galaxy radial velocities in the field of 18 APM clusters with redshifts between 0.06 and 0.13. The clusters have Abell identifications and the galaxies were selected within 0.75 h$^{-1}$Mpc in projection from their centers. We derive new cluster velocity dispersions for 13 clusters using our data and published radial velocities. We analyze correlations between cluster velocity dispersions and cluster richness counts as defined in Abell and APM catalogs. The correlations show a statistically significant trend although with a large scatter suggesting that richness is a poor estimator of cluster mass irrespectively of cluster selection criteria and richness definition. We find systematically lower velocity dispersions in the sample of Abell clusters that do not fulfill APM cluster selection criteria suggesting artificially higher Abell richness counts due to contamination by projection effects in this subsample.Comment: Accepted for publication in MNRA

Occupational Segregation by Race and Ethnicity in the US: Differences across States

Using the 2005–2007 American Community Survey, we analyze the occupational segregation of workers by race and ethnicity across states. Although the unconditional analysis shows great geographical variation in segregation, with the largest levels in the Southwest, the analysis of segregation conditioned on the distribution of characteristics reveals that segregation of workers with similar characteristics is generally greater in the East Central region. To quantify conditional segregation, we adapt a propensity score technique that simultaneously controls for several characteristics, allowing the identification of the factors that explain the geographical variation of unconditional segregation.