1,721,143 research outputs found
Two-step estimation in linear regressions with adaptive learning
Full text linkWeak consistency and asymptotic normality of the ordinary least-squares
estimator in a linear regression with adaptive learning is derived when the
crucial, so-called, `gain' parameter is estimated in a first step by nonlinear
least squares from an auxiliary model. The singular limiting distribution of
the two-step estimator is normal and in general affected by the sampling
uncertainty from the first step. However, this `generated-regressor' issue
disappears for certain parameter combinations
Lempp, Jakob/Sebastian Mayer/Alexander Brand (Hrsg.) (2020): Die politischen Systeme Zentralasiens. Interner Wandel, externe Akteure, regionale Kooperation. Springer VS. Wiesbaden
No full textVasilache A. Lempp, Jakob/Sebastian Mayer/Alexander Brand (Hrsg.) (2020): Die politischen Systeme Zentralasiens. Interner Wandel, externe Akteure, regionale Kooperation. Springer VS. Wiesbaden. Politische Vierteljahresschrift (PVS). 2021;62(2):379–381
Asymptotic properties of endogeneity corrections using nonlinear transformations
No full textThis paper studies the asymptotic properties of endogeneity corrections based on nonlinear transformations without external instruments, which were originally proposed by Park and Gupta (2012) and have become popular in applied research. In contrast to the original copula-based estimator, our approach is based on a nonparametric control function and does not require a conformably specified copula. Moreover, we allow for exogenous regressors, which may be (linearly) correlated with the endogenous regressor(s). We establish consistency, asymptotic normality and validity of the bootstrap for the unknown model parameters. An empirical application on wage data of the US current population survey demonstrates the usefulness of the method
Estimation and Inference in Factor Copula Models with Exogenous Covariates
Full text linkA factor copula model is proposed in which factors are either simulable or
estimable from exogenous information. Point estimation and inference are based
on a simulated methods of moments (SMM) approach with non-overlapping
simulation draws. Consistency and limiting normality of the estimator is
established and the validity of bootstrap standard errors is shown. Doing so,
previous results from the literature are verified under low-level conditions
imposed on the individual components of the factor structure. Monte Carlo
evidence confirms the accuracy of the asymptotic theory in finite samples and
an empirical application illustrates the usefulness of the model to explain the
cross-sectional dependence between stock returns
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
Single-ion conducting multi-block copolymer electrolyte for Lithium-metal batteries with High mass loading NCM811 cathodes
No full textLithium-metal batteries comprising a single-ion conducting polymer electrolyte and a nickel-rich LiNi1-x-yCoxMnyO2 (NCM) positive electrode (cathode) potentially offer very high energy density and great safety. However, such cell chemistry is very demanding concerning the required interfacial stability of the polymer electrolyte, and the realization of high mass loading cathodes remains a great challenge. Herein, the development of a new single-ion conducting multi-block copolymer electrolyte including trifluoromethyl groups in the ionophilic block is reported. After ethylene carbonate (EC) is incorporated into the self-standing and easily processable polymer membranes, high ionic conductivity along with very high limiting current density and suitable anodic stability are obtained. These enable stable cycling of Li∥NCM811 cells─also at high C rates (up to 5C) and active material mass loadings of the NCM811 cathode of >10 mg cm–2, which are both key steps toward the potential commercialization of this class of electrolytes
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
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