1,721,166 research outputs found
Functional estimation of diversity profiles
No full textIt is well known that the diversity profile provides a complete picture about the evenness of the relative abundance distribution of an ecological population. This complexity measure is a continuous function evaluated on a suitable grid of values x ≥ 0 that determine the measure's sensitivity to the most dominant species. In this paper, a functional design-based estimation of diversity profiles is developed by applying a framework based on functional data analysis (FDA). These curves, which are positive, decreasing, and convex, can be viewed as constrained functional data. Therefore, a naive direct application of the FDA methodology can be misleading, both theoretically and practically. To tackle this problem, the diversity profile is defined in terms of a differential equation, in such a manner that the function to be estimated is unconstrained. An approximation of the bias and the variance of the estimator is derived using the delta method. The accuracy of the proposed functional constrained estimator is evaluated through a simulation study. The procedure is also applied on a real dataset concerning tree stem diameter diversity
Boundaries of the business model within business groups
No full textScholars have sought various ways to find out how financial performance of the firm can be affected by its business model (BM). However, to date academic literature has focused attention on the “firm” as a unit of analysis without clearly defining the boundaries of the reporting entity to which the BMs refer. The aim of this paper is to investigate what are the boundaries of the BM of the affiliated–group companies and how the degree of independence of BMs is measured within the business group. The contribution of the paper is in using the BM concept to expound and criticise the assumptions in economic analysis and accounting standards that groups of companies are economic units that optimise economic income of the group as a whole and that the financial statements of individual subsidiaries, sub-groups and the group as a whole report the value generated by the group
Detecting patterns in financial data through weighted time-frequency domain clustering
No full textThe paper introduces a strategy for identifying representative patterns in financial time series data from both temporal and frequency perspectives. To this end, a wavelet transformation of the time series is adopted as pre-processing step. Wavelets provide a multi-resolution representation of the time series, which is represented as the sum of a coarse approximation and a set of multiscale detail coefficients providing information about the temporal data at different frequency levels. This allows highlighting trends and cycles in the time domain, also assessing variance at different frequency levels. The contribution of this paper is the development of a clustering method for time series, represented as a matrix of wavelet coefficients to discover interesting patterns. To this end, an optimally weighted Euclidean distance is proposed, giving weights to frequency components. Thus, a new clustering objective function and an algorithm that allows optimizing it are proposed. The effectiveness of the method is evaluated on real and simulated data. The real dataset consists of a set of time series that record the Purchase Price for End Customers (PUN) of the Italian electricity market from 2016 to 2023, while the simulated dataset consists of time series generated by overlapping sinusoids with different amplitudes, frequencies, and phases
Mediterranean Diet Patterns in the Italian Population: A Functional Data Analysis of Google Trends
No full text
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
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
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