15,945 research outputs found
Inflated Beta Distributions
This paper considers the issue of modeling fractional data observed in the
interval [0,1), (0,1] or [0,1]. Mixed continuous-discrete distributions are
proposed. The beta distribution is used to describe the continuous component of
the model since its density can have quite diferent shapes depending on the
values of the two parameters that index the distribution. Properties of the
proposed distributions are examined. Also, maximum likelihood and method of
moments estimation is discussed. Finally, practical applications that employ
real data are presented.Comment: 15 pages, 4 figures. Submitted to Statistical Paper
Local power of the LR, Wald, score and gradient tests in dispersion models
We derive asymptotic expansions up to order for the nonnull
distribution functions of the likelihood ratio, Wald, score and gradient test
statistics in the class of dispersion models, under a sequence of Pitman
alternatives. The asymptotic distributions of these statistics are obtained for
testing a subset of regression parameters and for testing the precision
parameter. Based on these nonnull asymptotic expansions it is shown that there
is no uniform superiority of one test with respect to the others for testing a
subset of regression parameters. Furthermore, in order to compare the
finite-sample performance of these tests in this class of models, Monte Carlo
simulations are presented. An empirical application to a real data set is
considered for illustrative purposes.Comment: Submitted for publicatio
Evaluating Research Activity:Impact Factor vs. Research Factor
The Impact Factor (IF) âhas moved ... from an obscure bibliometric indicator to become the chief quantitative measure of the quality of a journal, its research papers, the researchers who wrote those papers, and even the institution they work inâ ([2], p. 1). However, the use of this index for evaluating individual scientists is dubious. The present work compares the ranking of research units generated by the Research Factor (RF) index with that associated with the popular IF. The former, originally introduced in [38], reflects article and book publications and a host of other activities categorized as coordination activities (e.g., conference organization, research group coordination), dissemination activities (e.g., conference and seminar presentations, participation in research group), editorial activities (e.g., journal editor, associate editor, referee) and functional activities (e.g., Head of Department). The main conclusion is that by replacing the IF with the RF in hiring, tenure decisions and awarding of grants would greatly increase the number of topics investigated and the number and quality of long run projects.scientific research assessment, Impact Factor, bibliometric indices, feasible Research Factor
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