Sub-field normaliztion in the multiplicative case : high- and low- impact citation indicators

This paper uses high- and low-impact citation indicators for the evaluation of the citation performance of research units at different aggregate levels. To solve the problem of the assignment of individual articles to multiple sub-fields, it follows a multiplicative strategy according to which each paper is wholly counted as many times as necessary in the several categories to which it is assigned at each aggregation level. To control for wide differences in citation practices at the lowest level of aggregation, we apply a novel sub-field normalization procedure in the multiplicative case. The methodology is applied to a partition of the world into three geographical areas: the U.S., the European Union (EU), and the Rest of the World. The main findings are the following two. (i) Although normalization does not systematically bias the results against any area, it reduces the U.S./EU highimpact gap in the all-sciences case by a non-negligible 14.4%. (ii) The dominance of the U.S. over the EU in the basic and applied research published in the periodical literature is almost universal at all aggregation levels. From the high-impact perspective, for example, the U.S. is ahead of the EU in 77 out of 80 disciplines, and all of 20 fields. For all sciences as a whole, the U.S. high-impact indicator is 61% greater than that of the EU. The authors acknowledge financial support from the Santander Universities Global Division of Banco Santander. Ruiz-Castillo also acknowledges financial help from the Spanish MEC through grant SEJ2007- 67436. This paper is part of the SCIFI-GLOW Collaborative Project supported by the European Commission.s Seventh Research Framework Programme, Contract number SSH7-CT-2008-217436 European Community's Seventh Framework Program.

Sub-field normalization in the multiplicative case: average-based citation indicators

This paper investigates the citation impact of three large geographical areas –the U.S., the European Union (EU), and the rest of the world (RW)– at different aggregation levels. The difficulty is that 42% of the 3.6 million articles in our Thomson Scientific dataset are assigned to several sub-fields among a set of 219 Web of Science categories. We follow a multiplicative approach in which every article is wholly counted as many times as it appears at each aggregation level. We compute the crown indicator and the Mean Normalized Citation Score (MNCS) using for the first time sub-field normalization procedures for the multiplicative case. We also compute a third indicator that does not correct for differences in citation practices across sub-fields. It is found that: (1) No geographical area is systematically favored (or penalized) by any of the two normalized indicators. (2) According to the MNCS, only in six out of 80 disciplines –but in none of 20 fields– is the EU ahead of the U.S. In contrast, the normalized U.S./EU gap is greater than 20% in 44 disciplines, 13 fields, and for all sciences as a whole. The dominance of the EU over the RW is even greater. (3) The U.S. appears to devote relatively more –and the RW less– publication effort to subfields with a high mean citation rate, which explains why the U.S./EU and EU/RW gaps for all sciences as a whole increase by 4.5 and 5.6 percentage points in the un-normalized case.

AN ALGORITHM TO REDUCE THE OCCUPATIONAL SPACE IN GENDER SEGREGATION STUDIES

This paper presents an algorithm based on the bootstrap to select an admissible aggregation level, that is, the minimum number of occupational categories which yield a gender segregation value which is not significantly smaller than that obtained from the large number of occupational categories usually available in any data set. The approach is illustrated using Labor Force Survey data for Spain for the comparison of gender segregation in 1977 and 1992, as well as 1994 and 2000. To measure gender segregation, an additively decomposable segregation index based in the entropy concept is used. Despite a substantial simplification in the size of the occupation’s space, the decrease in the segregation index is very small and not significant, regardless of the year. Consequently, intertemporal changes in gender segregation can be studied using a greatly reduced classification of occupations that permits an easier interpretation of results.

Tracking of a Basketball Using Multiple Cameras

Projecte final de carrera fet en copl.laboració amb École Polytechnique Fédérale de LaussanneThis master thesis presents a method for tracking a basketball during a basketball match recorded with a multi-camera system. We first developed methods to detect a ball in images based on its appearance. Color was used through a color histogram of the ball, manually initialized with ball samples. Then the shape of the ball was used in two different ways: by analyzing the circularity of the ball contour and by using the Hough transform to find circles in the image. In a second step, we attempted to track the ball in three dimensions using the cameras calibration, as well as the image methods previously developed. Using a recursive tracking procedure, we define a 3-dimensional search volume around the previously known position of the ball and evaluate the presence of a ball in all candidate positions inside this volume. This is performed by projecting the candidate positions in all camera views and checking the ball presence using color and shape cues. Extrapolating the future position of the ball based on its movements in the past frames was also tested to make our method more robust to motion blur and occlusions. Evaluation of the proposed algorithm has been done on a set of synchronized multi-camera sequences. The results have shown that the algorithm can track the ball and find its 3D position during several consecutive frames

An algorithm to reduce the occupational space in gender segregation studies.

This paper presents an algorithm based on the bootstrap to select an admissible aggregation level, that is, the minimum number of occupational categories that yield a gender segregation value not significantly smaller than that obtained from the large number of occupational categories usually available in any data set. The approach is illustrated using labour force survey data for Spain for the comparison of gender segregation in 1977 and 1992, as well as 1994 and 2000. To measure gender segregation, an additively decomposable segregation index based on the entropy concept is used. Despite a substantial simplification in the size of the occupation space, the decrease in the segregation index is very small and not significant, regardless of the year. Consequently, intertemporal changes in gender segregation can be studied using a greatly reduced classification of occupations that permits an easier interpretation of results.

Multiplicative and fractional strategies when journals are assigned to several sub-fields

In many datasets, articles are classified into sub-fields through the journals in which they have been published. The problem is that many journals are assigned to a single sub-field, but many others are assigned to several sub-fields. This paper discusses a multiplicative and a fractional strategy to deal with this situation, and introduces a normalization procedure in the multiplicative case that takes into account differences in mean citation rates across sub-fields. The empirical part studies different aspects of citation distributions under the two strategies, namely: (i) the number of articles, (ii) the mean citation rate, (iii) the broad shape of the distribution, (iv) the characterization in terms of size- and scale-invariant indicators of high- and low-impact, and (v) the presence of extreme distributions, or distributions that behave very differently from the rest. It is found that, in spite of large differences in the number of articles according to both strategies, the similarity of the citation characteristics of articles published in journals assigned to one or several sub-fields guarantees that choosing one of the two strategies may not lead to a radically different picture in practical applications. Nevertheless, the evaluation of citation excellence through a high-impact indicator may considerably differ depending on that choice.The authors acknowledge financial support by Santander Universities Global Division of Banco Santander. Ruiz-Castillo acknowledges financial support from the Spanish MEC through grant SEJ2007-67436European Community's Seventh Framework Progra

Sub-field normalization in the multiplicative case : high- and low- impact citation indicators

This paper uses high- and low-impact citation indicators for the evaluation of the citation performance of research units at different aggregate levels. To solve the problem of the assignment of individual articles to multiple sub-fields, it follows a multiplicative strategy according to which each paper is wholly counted as many times as necessary in the several categories to which it is assigned at each aggregation level. To control for wide differences in citation practices at the lowest level of aggregation, we apply a novel sub-field normalization procedure in the multiplicative case. The methodology is applied to a partition of the world into three geographical areas: the U.S., the European Union (EU), and the Rest of the World. The main findings are the following two. (i) Although normalization does not systematically bias the results against any area, it reduces the U.S./EU highimpact gap in the all-sciences case by a non-negligible 14.4%. (ii) The dominance of the U.S. over the EU in the basic and applied research published in the periodical literature is almost universal at all aggregation levels. From the high-impact perspective, for example, the U.S. is ahead of the EU in 77 out of 80 disciplines, and all of 20 fields. For all sciences as a whole, the U.S. high-impact indicator is 61% greater than that of the EU.The authors acknowledge financial support from the Santander Universities Global Division of Banco Santander. Ruiz-Castillo also acknowledges financial help from the Spanish MEC through grant SEJ2007- 67436. This paper is part of the SCIFI-GLOW Collaborative Project supported by the European Commission’s Seventh Research Framework Programme, Contract number SSH7-CT-2008-217436European Community's Seventh Framework Progra

De l'epiteli de ceba a la indagació : un marc per a construir pràctiques investigadores cap a la Competència Científica

El desenvolupament de les dimensions de la competència científica (conceptual, procedi-mental i epistèmica) té en els treballs pràctics de laboratori un espai candidat. El desple-gament de pràctiques investigadores és complex i requereix de marcs metodològics i su-ports per dur-lo a terme. S'ha desenvolupat un marc metodològic per al treball estructurat amb pràctiques investigadores i bastides de suport i aplicat en una pràctica sobre biologia cel·lular i microscòpia. El marc metodològic proposa diverses bastides de suport per al treball d'habilitats de raonament científic i una seqüència de treball en 5 etapes que culmi-na en l'escriptura d'un article científic per part dels alumnes. Es justifiquen i descriuen les diferents etapes i els resultats obtinguts i es comenten dinàmiques clau (oralitat, auto i co-avaluació) i l'aportació d'aquest tipus de pràctiques a les tres dimensions de la competèn-cia científica.Practical laboratory work is a candidate space to develop the conceptual, procedural and epistemic dimensions of scientific competence. Developing inquiry practices is complex and requires methodologic frames and didactic scaffolds. We have developed a methodo-logic frame for structured inquiry activities and applied it to an activity on microscopy and cell biology. The proposed frame includes several scaffolds for scientific research proces-ses and follows 5 steps resulting in a Scientific Article written by students from their re-search. We describe and justify each of these steps and discuss some key dinàmics (oral communication, co- and self-assessment) and the impact of this kind of practices on the three dimensions of the scientific competence

Sub-field normalization in the multiplicative case : average-based citation indicators

This paper investigates the citation impact of three large geographical areas –the U.S., the European Union (EU), and the rest of the world (RW)– at different aggregation levels. The difficulty is that 42% of the 3.6 million articles in our Thomson Scientific dataset are assigned to several sub-fields among a set of 219 Web of Science categories. We follow a multiplicative approach in which every article is wholly counted as many times as it appears at each aggregation level. We compute the crown indicator and the Mean Normalized Citation Score (MNCS) using for the first time sub-field normalization procedures for the multiplicative case. We also compute a third indicator that does not correct for differences in citation practices across sub-fields. It is found that: (1) No geographical area is systematically favored (or penalized) by any of the two normalized indicators. (2) According to the MNCS, only in six out of 80 disciplines –but in none of 20 fields– is the EU ahead of the U.S. In contrast, the normalized U.S./EU gap is greater than 20% in 44 disciplines, 13 fields, and for all sciences as a whole. The dominance of the EU over the RW is even greater. (3) The U.S. appears to devote relatively more –and the RW less– publication effort to subfields with a high mean citation rate, which explains why the U.S./EU and EU/RW gaps for all sciences as a whole increase by 4.5 and 5.6 percentage points in the un-normalized case. The results with a fractional approach are very similar indeedFinancial support from the Santander Universities Global Division of Banco Santander. Ruiz-Castillo also acknowledges financial help from the Spanish MEC through grant SEJ2007-67436European Community's Seventh Framework Progra