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C.R. Rao
No full textAbstract
C.R. Rao is a great name from the golden age of statistics. His work was done in India; his intellect shaped statistics worldwide. Julian Champkin talked to him in London.</jats:p
Remembering C.R. Rao (1920–2023)
No full textLast year, the scientific world lost one of its preeminent statisticians, Calyampudi
Radhakrishna Rao. Much has already been written about his more famous results, the
Cramér-Rao lower bound, the Rao-Blackwell Theorem, and information geometry. (The
August 2021 issue of the International Statistical Review provides a good primer.) Instead,
this memorial column will connect two applied publications Rao worked on early in his
career to modern data science:
(1) “Anthropometric survey of the United Provinces, 1941: A statistical study” by P.C.
Mahalanobis, D.N. Majumdar, M.W.M Yeatts, and C.R. Rao published in Sankhyā in
1949; and
(2) The Ancient Inhabitants of Jebel Moya by R. Mukherjee, C.R. Rao, and J.C. Trevor,
published in 1955.
Both works offer the contemporary reader excellent examples of following a modern
collaborative data science framework, from study design to data stewardship. We will focus
on three themes integrated within such frameworks: replicability, reproducibility, and
incorporating data context. (Replicability is the idea that a new study can repeat the results
of the old one. It implies, however, that the initial study provide sufficient details so that
someone else can "replicate" it, starting from data collection. This differs from
reproducibility, where researchers supply enough information, including the raw data, so
that the existing results can be independently generated. That said, especially given that
these are historical data sets, replicability can only be discussed as a theoretical possibility.
The quest for nonlinearity in time series
No full textIn this chapter, we review the problem of testing for nonlinearity in time series. First, we discuss the definition and the properties of linear processes and the implications that such properties have on the operational strand. Then, we present and review a tentative classification of the various tests that can be found both in the
time series and in the nonlinear dynamics literature. Two main factors contributed to the production of a plethora of alternatives for assessing nonlinearity in time series: the first factor is the intrinsic asymmetry between the linear and the nonlinear
realm. In fact, there can be departures from linearity in various directions as nonlinear phenomena possess a virtually infinite richness of features. Among such features we can mention irreversibility, nonuniform predictability, noise amplification/
suppression, phase synchronization, noise-induced phenomena, sensitivity to initial conditions, and so on. The second factor is the multidisciplinary nature of the problem. Indeed, the problem of characterizing the various aspects of nonlinear processes is shared among different disciplines, such as Statistics, Econometrics,
Nonlinear Dynamics, Biology, and Engineering. The review is by no means exhaustive and reflects the personal inclinations of the autho
Estimation of Complex Population Parameters Under the Randomized Response Theory
No full textWhen a sensitive quantitative variable is under study and the Randomized Response Theory is adopted, a great deal of literature has been devoted to the estimation of the population mean (or total) or - at most - simple functions of population totals. However, in many real surveys the main interest might rely on the estimation of a complex parameter, usually a nonlinear combination of population totals. Hence, in order to face with this problem, we suppose to collect data by means of the well-known unrelated question method proposed by Greenberg et al. (1971), and under the design-based framework, we propose to handle such a complex parameter as a population functional by suitably extending the linearization approach proposed by Deville (1999). The considered strategy permits to obtain parameter estimation by means of the substitution method based on the empirical functional, and to achieve the corresponding variance estimator. Some selected illustrative examples are provided mostly concerning the estimation of two inequality indices, namely the Gini concentration index and the Atkinson index, widely discussed in the social and economic literature
C.R. Rao: a beacon of excellence in statistical research and practice
No full textThis talk shines a spotlight on the remarkable achievements of C.R. Rao, an eminent statistician and mathematician, whose contributions have illuminated the field of statistics and related areas. Rao's transformative ideas in estimation theory, sufficiency and completeness, experimental design, biometry and data science, have revolutionized the way researchers approach data analysis and interpretation. Furthermore, his mentorship and educational efforts have fostered the growth of countless statisticians, ensuring his legacy
will continue for generations to come. The article underscores Rao's exceptional impact and highlights his numerous prestigious awards, solidifying his place as a beacon of excellence in the field. Some of the Rao's pivotal role in shaping the future of statistical research and practice will be presented.This research was partially funded by FCT—Fundação para a Ciência e a Tecnologia, under the project—
UIBD/00006/2020.info:eu-repo/semantics/publishedVersio
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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