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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Butterfly view of environmental variability in population dynamics across fragmented landscapes
Get PDFPopulation ecologists desire to understand how and why populations change over time. As demographic processes are variable and stochastic by nature, it is imperative to separate the intrinsic variability of population dynamics from external forces affecting movement, birth and, death of individuals comprising a population. At the same time, the interplay between environmental factors and demography does not allow for a clean separation of causes.
This thesis tries help tackle the statistical challenges of making sense of entangled causes and consequences, without suggesting that causal inference itself can rely on statistical tools alone. The methodological core of the thesis lies in variance partitioning, a method for quantifying "relative importance" of variables included in a model, in this case various environmental or biological covariates. While the use of variance partitioning has a long history in applied ecology, its limitations and uncertainties have often been ignored, just as the scope of its applicability has not been fully appreciated. This thesis presents variance partitioning as a general framework for working with a wide class of linear models, such as generalized linear models, and various "mixed-effects" and "additive" models. It also presents extensions to the method, a consistent treatment of uncertainty for the Bayesian case as well as related metrics which aid in the interpretation of variance partitions in the ubiquitous presence of correlations.
Specific aspects of the role of environmental variability are of great applied interest, especially as they relate to the persistence of populations. Towards that end, the methods in this thesis are applied to and demonstrated with a model system of metapopulation ecology, the long-term surveys of the Glanville fritillary butterfly in the Åland Islands. This thesis looks at the role of habitat heterogeneity and genetic variability in the persistence of metapopulations, affirming the large role for habitat quality in governing local population persistence. At the same time the role of variability in a dispersal-related gene demonstrates the complex ecoevolutionary dynamics of fragmented landscapes. The independence of local populations is a cornerstone of persistence of metapopulations. An increasing extent of weather phenomena and an increase in the spatial correlation of population dynamics of the butterfly across Åland show a clear link suggesting detereorating conditions for metapopulation persistence.
Another aspect affected by the environment is the relationship between the occurrence of a species and the numbers in which it occurs. This thesis shows a consistent relationship between occupancy and abundance in the large-scale and long-term study of the Glanville fritillary butterfly. In the context of metapopulations such a relationship will arise already due to the basic demographic processes involved. However, the results also show that this rather noisy relationship cannot be without due care be used to substitute occupancy for abundance to predict outcomes such as risk of local extinction.
The thesis highlights how population ecology needs tools to study the multitude of phenomena affecting populations and that ideally those tools should both be compatible with representing the processes studied, as well as easily communicable. In the context of statistical studies on observational data, variance partitioning can be of aid in terms of communicability, but on its own it will not solve the challenges of ecological relevance and model formulation - population ecologists still have their work cut out for them.Populaatioekologia tarkastelee lajien esiintymiseen ja runsauteen vaikuttavia tekijöitä ja niiden vaikutusten muutoksia ajan kuluessa. Yksilötasolla tarkasteltujen syntyvyyden, kuolleisuuden ja liikkuvuuden muutokset näkyvät populaatiotasolla kannanvaihteluna ja levinneisyyden muutoksina. Sekä lajin ominaispiirteet että ulkoiset tekijät kuten ympäristöolosuhteet vaikuttavat näihin prosesseihin, ja populaatioihin vaikuttavien ympäristötekijöiden tunnistaminen on yksi populaatioekologian keskeinen tehtävä.
Tämän tutkielman tavoite on tilastollisin keinoin auttaa tunnistamaan ympäristön vaikutusta populaatioihin havaintoaineistoista, joissa ympäristötekijöiden määrä on suuri. Tutkielman menetelmien keskiössä on varianssihajotelma, jolla voidaan osana tilastollista mallinnusta määrittää erilaisten ympäristö- ja biologisten muuttujien osalta niiden potentiaalinen suhteellinen merkitys kannanvaihteluissa. Varianssihajotelmia on pitkään käytetty osana soveltavaa ekologista tutkimusta, mutta siihen liittyviä haasteita ja epävarmuuksia ei aina ole huomioitu eikä toisaalta menetelmän kaikkia mahdollisuuksiakaan ole hyödynnetty. Menetelmä esitetään tässä tutkielmassa yleisenä työkaluna erilaisten regressiomallien kanssa työskentelyyn ja tarkastellaan etenkin epävarmuutta sekä vaihtoehtoisia varianssimittoja, jotka auttavat tulkitsemaan korreloituneita tekijöitä.
Tutkimuksen aineistona ovat Ahvenanmaan täpläverkkoperhosen pitkäaikaiset metapopulaatiobiologiset seurantatutkimukset. Tutkielmassa osoitetaan, että elinympäristön laadun vaihtelulla on suuri merkitys perhosen populaatioiden ja siten metapopulaatioiden pysyvyydelle. Samalla lentokykyyn liittyvässä geenissä olevan vaihtelun vaikutus kantojen pysyvyyteen muistuttaa kytkennöistä ekologian ja evoluutiobiologian välillä. Tutkielmassa tarkastellaan myös ympäristötekijöiden vaikutusta lajin esiintymisen ja yksilörunsauden väliseen suhteeseen. Kuten populaatioekologian näkökulmasta on odotettavissa, näkyy tässä tutkimuksessa selkeä suhde esiintyvyyden ja perhosen runsauden välillä. Tämä yhteys on kuitenkin pitkän ajan keskiarvo, eivätkä lajin esiintymistä kuvaavat aineistot voi yleisesti korvata tarkempaa yksilömäärän tai runsauden seurantaa esimerkiksi ennustettaessa populaatioiden pysyvyyttä.ei saavutettav
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
Niittytalouden loppu Nummenpään kylässä
No full textTutkielmassa tarkastelen niittytalouden loppua Nurmijärvellä sijaitsevassa Nummenpään kylässä 1800-luvulta lopulta 1900-luvun puoliväliin. Käytän aineistona ensisijaisesti historiallisia karttoja ja maatalouslaskentojen alkuperäisaineistoja. Lisäksi arvioin kyseisten aineistojen soveltuvuutta historiallisen ekologian ja pitkäaikaisten muutosten tutkimukseen.
Digitoin historiallisilta kartoilta maataloudellisen maankäytön ja analysoin sen muutoksia eri aikoja kuvaavien karttojen välillä. Maatalouslaskenta-aineistoista analysoin niittyjen esiintymistä viljelmillä logistisella regressiomallilla. Niittytalous loppui Nummenpäässä viimeistään 1910-luvulla, aikaisemmin kuin Nurmijärvellä keskimäärin. Vuosien 1870–1930 välillä suurin osa niittymaasta raivattiin pelloksi. Alaa, joka oli 1800- ja 1900 -luvun vaihteessa ollut niittynä, oli 1930 jäljellä enää muutamama prosentti alkuperäisestä.
Viljelmät eivät vielä erikoistuneet tuotantosuunnittain tutkimuksen ajanjaksona, mutta koneellistuminen ja painotus kotieläintuotantoon kasvoivat. Viljelmien välillä ei ollut riittävästi vaihtelua löytämään selkeitä niittyjen käytön loppumiseen liittyviä tekijöitä. Niittytalous saattoi myös loppua niin varhain, että selkeä yhteys maatalouden tuotantorakenteen ja niittyjen esiintymisen välillä oli jo katkennut.
Tutkielmassa käytetyt tilastot ja kartat eivät olleet ajallisesti tarpeeksi kattavia selvittämään niittytalouden lopun maisemanmuutosta sekä sitä ajaneita tekijöitä ja aineistojen analysointi erikseen ei tukenut tavoitetta yhdistää sosioekonomiset muutokset maisemanmuutokseen.
Arvioin silti, että tutkielmassa käytetyt sekä muut saatavilla olevat historialliset aineistot sopivat hyvin historiallisiin ekologisiin tutkimuksiin. Aineistoja tulee tarkastella historiallisen lähdekritiikin silmin ja analysoida yhdessä kokonaisuuksina eikä erillään. Käyttämällä sopivia spatiotemporaalisia malleja voisi aineistoista saada huomattavasti mielenkiintoisempia tuloksia ja vähentää aineiston epätarkkuuteen liittyviä ongelmia.In this thesis I study the end of meadow-based agriculture in the village of Nummenpää in the municipality Nurmijärvi from the 19th century to the mid 20th century. My primary source materials are historical maps of the region and the original survey forms of past agricultural censuses. I also appraise the utility of these materials for historical ecological research and the study of long term changes.
I digitized agricultural land use from historical maps and analyzed changes in land use by comparing maps from different time periods. The agricultural census records were analyzed with logistic regression to determine characteristics of farms relating to the presence of meadows.
Meadows had lost their role in agricultural production in Nummenpää before 1920, somewhat earlier than in Nurmijärvi on average. Between 1870 and 1930 most of the meadows had been ploughed into fields. Of meado land that had been meadow already at the turn of the century only a few percent remained in 1930.
Farms in Nummenpää had not yet differentiated into specialized crop production or animal husbandry during the study period, but mechanization proceeded and more emphasis was placed on cattle and dairy production. There was insufficient variability between farms to determine properties that could be associated with the end of the agricultural use of meadows. It is also possible, that meadows lost their role so early that there was no longer a clear link to the agricultural economy.
The census records and maps used in the study did not have sufficient temporal coverage and resolution to permit me to determine the dynamics of landscape change associated with the end of the meadow-based agriculture nor the factors driving the change. The separate analysis of map and census data was not conducive to linking socioeconomic change to landscape change.
Nonetheless, I maintain that the source materials used in the study, and other similar materials, are well suited for historical ecological research. The materials must be evaluated critically from a historical perspective and the analysis should integrate the distinct sources. By utilizing appropriate spatiotemporal models it should be possible to reach more interesting conclusions and reduce the impact of uncertainty and imprecision inherent in the materials
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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