1,721,276 research outputs found
Criticalities in applying the Neyman’s optimality in business surveys : a comparison of selected allocation methods
No full textIn finite population sampling, when dealing with negligible sampling fractions (budget
constraints) or when data quality is not satisfactory (e.g. frame lists, auxiliary information,
etc.), a rethinking of Tchuprow’s (1924) optimality concept (later extended by Neyman, 1934)
in stratified sampling is needed. In fact, the need of stratum representativeness from one side
and the optimum allocation from the other are often in conflict. Furthermore, the choice of a
sampling design which is rigorously respectful of the statistical theory is a difficult task in
practice, especially when knowledge barriers and operational constraints are present.
Sometimes a purposive design is the only possibility. This work aims at finding an optimal
allocation method from a population of enterprises. This task is carried out through a
simulation approach which compares different methodologies. We consider, among others,
and together with the popular optimal allocation and its multivariate extension (Bethel’s
algorithm -1989), the ‘Optimum Robust Allocation with Uniform Stratum Threshold –
AORSU’ (Chiodini P.M., Manzi G., Verrecchia F.; 2008) and the ‘dynamic allocation’
(Buisson, 2009). These methods are suitable both for domain analyses and for the
improvement of the estimates, obtained through a proxy of the stratum variability. In general,
AORSU is useful when an ex-ante allocation is possible. On the other hand the dynamic
allocation (i.e. ex-post) is becoming more and more of interest especially when no
information about stratum variability is available. The method relies on an in itinere adjustment process (i.e. an allocation based upon an estimate of the sampling variance of the first sampling data from the strata). For the latter method, even though a number of practical
solutions for the survey list are available (see, e.g., Chiodini P.M., Facchinetti, Manzi G., Nai Ruscone M., Verrecchia F, 2008), the substitution of sampling units to be interviewed, which is routinely performed, is the real practical drawback, especially when organizational problems, related to target shifting, arise. The solution to this is generally not trivial.
Simulations will be carried out on different databases (ASIA - ISTAT; Italian Register of
enterprises - Chamber of Commerce of Milan, Italy
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
Revisiting Sample Allocation Methods: A Simulation-Based Comparison
Full text linkIn stratified sampling the problem of optimally allocating the sample size is of primary importance, especially in business surveys when reliable estimates are required both for the overall population and for the domains of studies. To this purpose, in this paper we compare allocation methods via a simulation engine highlighting the effects on the reliability of the estimates due only to the sample allocation design. Allocation methods considered in this comparison are: the Neyman allocation, the uniform and proportional allocations, the Costa allocation, the Bankier allocation, the Interior Point Non Linear Programming allocation and the Robust Optimal Allocation with Uniform Stratum Threshold, an allocation method recently adopted by the Italian National Statistical Institute. The last two methods outperform the
others at the stratum level. At the overall sample level they perform better than the others together with the Neyman allocation method
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
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