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Kurtz, M.J.; Eichhorn, G.; Accomazzi, A.; Grant, C.; Demleitner, M.; Murray, S.S.: Worldwide use and impact of the NASA Astrophysics Data System Digital Library (2005)
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- Abstract
- The NASA Astrophysics Data System (ADS), along with astronomy's journals and data centers (a collaboration dubbed URANIA), has developed a distributed online digital library which has become the dominant means by which astronomers search, access, and read their technical literature. Digital libraries permit the easy accumulation of a new type of bibliometric measure: the number of electronic accesses ("reads") of individual articles. By combining data from the text, citation, and reference databases with data from the ADS readership logs we have been able to create second-order bibliometric operators, a customizable class of collaborative filters that permits substantially improved accuracy in literature queries. Using the ADS usage logs along with membership statistics from the International Astronomical Union and data an the population and gross domestic product (GDP), we have developed an accurate model for worldwide basic research where the number of scientists in a country is proportional to the GDP of that country, and the amount of basic research done by a country is proportional to the number of scientists in that country times that country's per capita GDP. We introduce the concept of utility time to measure the impact of the ADS/ URANIA and the electronic astronomical library an astronomical research. We find that in 2002 it amounted to the equivalent of 736 full-time researchers, or $250 million, or the astronomical research done in France.
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Kurtz, M.J.; Eichhorn, G.; Accomazzi, A.; Grant, C.; Demleitner, D.; Murray, S.S.; Martimbeau, N.; Elwell, B.: ¬The bibliometric properties of article readership information (2005)
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- Abstract
- Digital libraries such as the NASA Astrophysics Data System (Kurtz et al., 2005) permit the easy accumulation of a new type of bibliometric measure, the number of electronic accesses ("reads") of individual articles. We explore various aspects of this new measure. We examine the obsolescence function as measured by actual reads and show that it can be weIl fit by the sum of four exponentials with very different time constants. We compare the obsolescence function as measured by readership with the obsolescence function as measured by citations. We find that the citation function is proportional to the sum of two of the components of the readership function. This proves that the normative theory of citation is true in the mean. We further examine in detail the similarities and differences among the citation rate, the readership rate, and the total citations for individual articles, and discuss some of the causes. Using the number of reads as a bibliometric measure for individuals, we introduce the read-cite diagram to provide a two-dimensional view of an individual's scientific productivity. We develop a simple model to account for an individual's reads and cites and use it to show that the position of a person in the read-cite diagram is a function of age, innate productivity, and work history. We show the age biases of both reads and cites and develop two new bibliometric measures which have substantially less age blas than citations: SumProd, a weighted sum of total citations and the readership rate, intended to show the total productivity of an individual; and Read10, the readership rate for articles published in the last 10 years, intended to show an individual's current productivity. We also discuss the effect of normalization (dividing by the number of authors an a paper) an these statistics. We apply SumProd and Read10 using new, nonparametric techniques to compare the quality of different astronomical research organizations.
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Kurtz, M.J.; Eichhorn, G.; Accomazzi, A.; Grant, C.; Demleitner, M.; Henneken, E.; Murray, S.S.: ¬The effect of use and access on citations (2005)
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