1,721,310 research outputs found
Surviving Survivorship Bias
No full textThe purpose of this study is twofold:
First: to introduce a new notion of survivorship bias for mutual fund data taking into account the fact that cancellation or termination of fund records may have both a positive and a negative effect on the overall evaluation of performance
Second: to analyze in detail the most widely used dataset for mutual fund performance evaluation: CRSP to assess whether such a dataset possesses the properties needed for being a sound basis for performance evaluation and, in particular, for the estimation of survivorship bias effects.
A third and strictly connected purpose: the statement and estimation of a survival model for survivorship bias correction, shall be pursued in a following paper.
The standard statement of the problem can be simply subsumed: mutual funds with poor performance close down and are forgotten in standard databases. Hence, the use of such databases for the assessment of overall fund performance is bound to yield upward biased results. Inclusion of the deleted fund result in the database solves the problem.
The implied assumption is that a full correction for the deletion of funds from the database can be accomplished simply adding to the database all the deleted funds, with no further correction.
This assumption about dataset completion, only holds if we suppose that deletion of funds to be a random event. In this case, however, fund deletion shall not create any bias in the overall analysis of the industry performance even if deleted funds are not reinserted in the dataset.
If, as it is likely, fund deletion depends on fund performance (so that a problem of bias may exist), the simple reintroduction of deleted data in the dataset shall not “correct” the bias.
In fact the only way, in this case, for correcting the bias is to study the interaction between the NAV process and the censoring rule, or, in other words, the survival model.
Any different NAV model joint to a survival model shall yield different bias evaluation and the simple trick of “completing” the dataset cannot solve such a problem.
In order to understand this, it is useful to realize that, ideally, the “complete”, bias free, dataset should contain the full history of “revived” funds run from the date of their demise to the date of observation of the dataset. Since this completion is impossible, the only alternative, as said above, is to study the interplay between the NAV model and the censoring rule.
In the first part of the empirical analysis, survivorship bias is estimated according to its standard definition, that is: as the difference in performance between the set of surviving mutual funds and the set of all mutual funds existed in a specific time period. After excluding from the analysis all the funds for which data are missing, 29258 equity mutual funds that existed between January 2000 and December 2011 are analyzed.
The difference in performance between survived and dead funds is positive and bigger the higher is the time horizon considered. However, the number of surviving mutual funds underperforming non-surviving ones is always very high suggesting that performance is not enough to explain mutual fund survival.
In the second part of the analysis, data on fund volatility, age, size, target, turnover, expenses and sensitivity to risk factors are employed as explanatory variables for survival. Survival is evaluated in 6 different points in time for a time horizon of 6 years. Size, turnover and expenses seem to matter in explaining mutual fund survival suggesting that stochastic survival models should be built considering these variables in addition to performance
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
Dispelling 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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