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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
An analysis of the role of financialisation, China and stockholding in agricultural commodity price movements
No full textA wide range of commodity prices experienced a large peak in 2007/08, including many agricultural commodities. Since then agricultural commodity prices have remained at relatively high levels compared to the recent past and several agricultural commodities (e.g. maize and sugar) have experienced further, although smaller peaks. Studies of the recent commodity price movements have focused on financialisation, China, low stocks and biofuels. This thesis explores the role of three of these factors in agricultural commodity price formation, namely, financialisation, China and stockholding. Biofuels were analysed in work for my previous employer.
The second chapter uses Granger-causality methods to assess whether index investor positions influence agricultural futures prices. Four extensions are explored that might overcome the limitations of Granger-causality tests in this context. Firstly, the analysis is extended to less liquid markets. Liquid markets tend to be relatively efficient and for those markets the semi-strong form of the Efficient Market Hypothesis suggests that prices should not be forecastable as new information is swiftly impounded in prices. Even if index investment had price impact finding Granger-causality based on weekly data would be surprising. In less liquid markets prices are likely to adjust more slowly to new information.
Three further extensions are examined: long-horizon tests, using relative returns instead of returns and an index of positions instead of positions in individual markets. The analysis supports the conclusion that no impacts are discernible for liquid markets. However, Granger-causality is established in the less liquid soybean oil and livestock markets. Thus, there is clear evidence that index investment has been a factor influencing the level of grains and livestock prices in illiquid markets over the five years 2006-11.These results lead to the conjecture that index investment does also have price impact in liquid markets but that market efficiency prevents the detection of this impact using Granger-causality tests.
Chapter 3 investigates the potential impacts of changes in Chinese stockholding and self-sufficiency policies on world wheat prices. Whether or not the decrease in world grain stocks around the middle of the 2000s has had a significant impact on world prices in the last decade is controversial. Since most of the decrease in stocks was due to decreases in China, the main issue is the role that China has played on world markets. So far most studies that address this question have relied on informal arguments rather than formal modelling of the stocks-trade-price relationships. More recently the impact of possible changes to China’s self-sufficiency policy on world markets has become the focus of attention.
Trade and other grains policies are closely linked. Any impact of changes in grain policy in China will be transmitted to the world market through changing trade patterns. The model shows that a move away from autarky reduces stock levels in China and in the rest of the world resulting in lower global stock levels. In the two scenarios where China imports but does not export global stocks decline by 23 and 32 per cent, respectively, compared to autarky. In the two free trade scenarios, global stocks reduce by 38 and 44 per cent, respectively, compared to autarky. These reductions in stock levels when a country moves from autarky to trading with the rest of the world do not lead to an increase in price variation and, more importantly for policy-makers, do not lead to increases in extreme price movements. In the free trade scenarios, extreme price movements are even reduced despite much lower stock levels.
Chapter 4 introduces a new approach to testing the competitive storage model which has been the main workhorse of the analysis of the role of storage in commodity price formation over the last decades. The relationship between storage and prices is complex. Stock levels depend on current prices and expected future prices. At the same time, the current prices and the futures expected price depend on the level of stocks carried forward from the current period to future periods.
The main approach to testing the competitive storage model has been the comparison of the characteristics of the predicted price series with actual commodity price series. In this study a different approach is taken. A relatively simple model is taken to the experimental laboratory. Participants in the experiment are asked to make storage decisions within a competitive storage model framework. Participants’ behaviour in the experiment deviated from the behaviour predicted by the competitive storage model in a number of ways. The predicted relationship between the amount of wheat available and storage is non-linear in the model but is linear in the experiment. In addition, storage is more sensitive to “wheat” in storage than “wheat” harvested when the model suggests that the effect of wheat in storage and wheat from harvest should the same. Furthermore, average storage tends below the optimal level and storage does not vary as much as predicted by the competitive storage model. The resulting price series tend to be more variable than would be the case if stockholders behaved according to the competitive storage model
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
An Experimental Approach to Testing the Competitive Storage Model
Full text linkA new approach to testing the competitive storage model is introduced. A relatively simple model is taken to the experimental laboratory. Market outcomes in the experiment deviate from the predictions of the competitive storage model in a number of ways. Average storage and the variability of storage are below the levels predicted by the competitive storage model. The resulting price series, therefore, tend to be more variable than would be the case if stockholders behaved according to the competitive storage model. In addition, the predicted relationship between availability and storage is non-linear but is linear in the experiment
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Rural development statistics in the ECE region: A new project
No full textDispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Are stockholders rational? An experimental approach to testing the competitive storage model
Full text linkThe competitive storage model has been the main workhorse of the analysis of the role of storage in commodity price formation since Gustafson proposed his model in 1958. The main approach to testing the competitive storage model has been the comparison of the characteristics of the predicted prices series with actual commodity price series. This paper introduces a new approach to testing the competitive storage model. A relatively simple model is taken to the experimental laboratory. Participants in the experiment are asked make storage decisions within a competitive storage model framework. Their behaviour and the resulting price series are compared to the model assumptions and predictions. The experiment will be run at the University of Trento in April 2014
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