1,720,959 research outputs found
A test to assess the dynamic evolution of preferences in marketing surveys
No full textThe subject of this paper is a two-stage hypothesis test, which may have interesting applications in several situations related to the opinion research field. Such test is based on the components of a Bivariate Correlated Normal random variable. In particular, it is based on the exact distribution of their minimum and maximum modulus. This test was proposed for the first time by Duncan in Miller (1981), and was recently improved by Pollastri (2008). In the latter paper a variant of such test is described, since two samples in two different times or situations are considered. Two kinds of applications are provided to show the wide range of usage
Confidence Intervals for The Ratio of Two Means Using the Distribution of the Quotient of Two Normals
No full textIn various scientific fields such as medicine, biology and bioassay, several ratio quantities assumed to be Normal, are of potential interest. The estimator of the ratio of two means is a ratio of two random variables normally or asymptotically normally distributed. The present paper shows the importance of considering the real distribution of the estimator of the ratio of two means, because generally the approximation to Normal is not satisfied. The estimated asymptotic cumulative and density function of the estimator of the ratio is presented, with several considerations on the skewness. Finally, a new method for building confidence intervals for the ratio of two means was proposed. In contrast to other parametric methods, this new method is worthy to be preferred because it considers the skewness in the distribution of the ratio estimator, and the confidence intervals are always bounded
Stimatori col metodo della regressione in caso di non rispondenti con un campionamento doppio
No full textThe aim of this paper is to study the procedures to estimate the mean of a variable in presence of non-respondents in a first sampling using the informations of a seconde sample among the non-respondents and the informations regarding the means of one or more auxiliaries variables. It is shown the variance of the regression estimator. Then it is proposed the estimation of the parameters of the linear model using the information of the first and the second sample
Cost-effectiveness ratio for comparing social and health policies
No full textThe analysis of the incremental cost-effectiveness ratio (ICER) is an important
part of the social and health decision-making process, because ICER is used to obtain
simultaneous information on the cost and effectiveness of a new intervention when compared
to another one. Despite the increasing use of the ICER, studies on its statistical
methodology have still not been sufficiently developed. In particular, the calculation of
the confidence interval for the ICER is fundamental to take into account the uncertainty
due to differences in samples. In this paper, a new parametric technique for the construction
of confidence intervals for the ICER is proposed. It is based on the distribution of the
ratio of two correlated normal variables. The method discussed has always existed, despite
the degenerate cases of the classical parametric method proposed by Fieller, for
which the classical region is not an interval. The computation of the confidence intervals
proposed in the present paper may also be achieved in a feasible way
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
Distribution of the ratio of female income over male income
No full textThere is a great discussion concerning the differences between the income of females and males. The purpose of the present study is to estimate the distribution of the ratio of female income over male income. The methodology to study the ratio in exam is based on the distribution of the ratio of two Dagum random variables with three parameters proposed in 2010 by Pollastri and Zambruno.
We will consider the official statistics of income and we will estimate the parameters of the Dagum distribution. The distribution of the ratio in question studied in two different situations can reveal the gender inequality concerning income in different times, regions, and age classes
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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