1,720,973 research outputs found
Estimation of the variance for different estimators of the change over time for overlapping samples
Full text linkThis work was inspired by the growing need to have a measure of the accuracy of the estimates produced within the short-term statistics in the Official Statistics. In particular, the aim of the work is to illustrate the methodology for the computation of the variance for the estimators currently used in the service turnover survey carried on by the Italian National Institute of Statistics, for the quarterly turnover growth rate estimation.
While the calculation of the variance of the estimates produced for a given instant of time is now a good practice (also through the development of software packages), the same does not happen for the variation of two quantities over time. An estimator of variance must take into account of both the estimator and the sampling design (Wolter, K.M. (1985)). The greatest difficulty is that for many surveys, the samples for producing estimates in two different time are not independent each other, due to the rotation operations of the sample. In particular for business surveys, in order to take into account the birth-mortality of units in the population and changes in stratification variables (such as size category and type of economic activity), the sample is updated, and a part of the units is replaced with others. Moreover, many indicators are non-linear function of linear estimators (e.g. simple ratio, difference of ratios), therefore, to calculate their variance a first-order Taylor approximation can be used. Alternatively, balanced repeated replication (BRR) can be used.
My methodological contribution is not only to suggest how to assess the variance of possible estimators of the turnover variation over time, but also to compare such estimators with respect to their variance to identify the best one. The performance of these estimators is assessed by a simulation study, which also has the aim of exploring under which conditions it is better to use all the observations or only the overlapping observations. The change estimators and the corresponding estimators of the variance are defined at stratum and estimation domain level and take into account the use of a stratified sampling design and the updating of the sample due to a replacement of some units and to a dynamic stratification of the population
SupplementaryMaterial_SMR_20191215 - A Logistic Regression Extension for the Randomized Response Simple and Crossed Models: Theoretical Results and Empirical Evidence
No full textSupplementaryMaterial_SMR_20191215 for A Logistic Regression Extension for the Randomized Response Simple and Crossed Models: Theoretical Results and Empirical Evidence by Shu-Hui Hsieh and Pier Francesco Perri in Sociological Methods & Research</p
Editorial to the special issue on “Advances in statistical modelling, methods and applications”
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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
Sequential and Two Phase Sample Designs for Quality Control
No full text.In the framework of the quality assessment of land cover databases, we have proposed the two-phase approach with permanent random numbers (TPPRN) and we have compared it with the adaptive sequential quality control with permanent random numbers (ASPRN) and with the two-phase sample design proposed by Thompson and Seber. Whatever the weights assigned to the estimators of the TPPRN, it is much more efficient than the two phase sample design proposed by Thompson and Seber. Moreover, in all the simulations, the efficiency of the TPPRN is comparable with the one of the ASPRN, although the TPPRN is much simpler.In the framework of the quality assessment of land cover databases, we have compared the two-phase approach with permanent random numbers (TPPRN) with the adaptive sequential quality control with permanent random numbers (ASPRN) and with the two-phase sample design proposed by Thompson and Seber. Whatever the weights assigned to the estimators of the TPPRN, it is much more efficient than the two phase sample design proposed by Thompson and Seber. Moreover, in all the simulations, the efficiency of the TPPRN is comparable with the one of the ASPRN, although the TPPRN is much simpler
Simultaneous Optimization for Two Stage Area Sampling
No full textA method for simultaneous optimization of all the parameters of a two-stage area sample design is proposed.
In area sample surveys, estimates precision is influenced by the size of the area units. Often, for reducing travel costs, a two stage sample design is adopted. In these cases, the size of primary
sampling units (PSUs) and secondary sampling units (SSUs) as well as the number of PSUs and SSUs to be selected can be chosen by the sampler. Carfagna (2000), under a fixed budget, computes the optimum SSU size for a single stage sampling, then
determines the optimum set of size of PSU and number of PSUs and SSU to be selected. This procedure assumes that PSUs are much larger than SSUs, thus clustering SSUs within PSUs does not affect the optimum size of SSUs. Although this assumption is reasonable, in this paper, we explore the possibility of simultaneous optimization for the set of variables involved in the two stage area sample design
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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