Field-Normalized Citation Impact Indicators and the Choice of an Appropriate Counting Method

Bibliometric studies often rely on field-normalized citation impact indicators in order to make comparisons between scientific fields. We discuss the connection between field normalization and the choice of a counting method for handling publications with multiple co-authors. Our focus is on the choice between full counting and fractional counting. Based on an extensive theoretical and empirical analysis, we argue that properly field-normalized results cannot be obtained when full counting is used. Fractional counting does provide results that are properly field normalized. We therefore recommend the use of fractional counting in bibliometric studies that require field normalization, especially in studies at the level of countries and research organizations. We also compare different variants of fractional counting. In general, it seems best to use either the author-level or the address-level variant of fractional counting.

[1]  Michael Schreiber.  A case study of the modified Hirsch index h m accounting for multiple coauthors , 2009 .

[2]  J. E. Hirsch,et al.  An index to quantify an individual's scientific research output , 2005, Proc. Natl. Acad. Sci. USA.

[3]  Javier Ruiz-Castillo,et al.  Sub-Field Normalization in the Multiplicative Case: Average-Based Citation Indicators , 2011, J. Informetrics.

[4]  Lutz Bornmann,et al.  Do Universities or Research Institutions With a Specific Subject Profile Have an Advantage or a Disadvantage in Institutional Rankings? A Latent Class Analysis With Data From the SCImago Ranking , 2013, J. Assoc. Inf. Sci. Technol..

[5]  Thed N. van Leeuwen,et al.  Towards a new crown indicator: Some theoretical considerations , 2010, J. Informetrics.

[6]  Pedro Albarrán,et al.  A comparison of the scientific performance of the U.S. and the European Union at the turn of the XXI century , 2009 .

[7]  Peder Olesen Larsen,et al.  The state of the art in publication counting , 2008, Scientometrics.

[8]  Wiley Interscience.  Journal of the American Society for Information Science and Technology , 2013 .

[9]  Ludo Waltman,et al.  An empirical analysis of the use of alphabetical authorship in scientific publishing , 2012, J. Informetrics.

[10]  Michael Schreiber,et al.  To share the fame in a fair way, hm modifies h for multi-authored manuscripts , 2008 .

[11]  Ludo Waltman,et al.  A review of the literature on citation impact indicators , 2015, J. Informetrics.

[12]  M Dym,et al.  Gossypol: effect on testosterone. , 1981, Science.

[13]  Dag W. Aksnes,et al.  Ranking national research systems by citation indicators. A comparative analysis using whole and fractionalised counting methods , 2012, J. Informetrics.

[14]  Benjamin F. Jones,et al.  Multi-University Research Teams: Shifting Impact, Geography, and Stratification in Science , 2008, Science.

[15]  Massimo Franceschet,et al.  The effect of scholar collaboration on impact and quality of academic papers , 2010, J. Informetrics.

[16]  Peder Olesen Larsen,et al.  Counting methods are decisive for rankings based on publication and citation studies , 2005, Scientometrics.

[17]  Mu-Hsuan Huang,et al.  Counting methods, country rank changes, and counting inflation in the assessment of national research productivity and impact , 2011, J. Assoc. Inf. Sci. Technol..

[18]  Nils T. Hagen,et al.  Harmonic Allocation of Authorship Credit: Source-Level Correction of Bibliometric Bias Assures Accurate Publication and Citation Analysis , 2008, PloS one.

[19]  Javier Ruiz-Castillo,et al.  Multiplicative versus fractional counting methods for co-authored publications. The case of the 500 universities in the Leiden Ranking , 2015, J. Informetrics.

[20]  Jonas Lundberg,et al.  Lifting the crown - citation z-score , 2007, J. Informetrics.

[21]  Leo Egghe.  Mathematical theory of the h- and g-index in case of fractional counting of authorship , 2008, J. Assoc. Inf. Sci. Technol..

[22]  Cassidy R. Sugimoto,et al.  Mapping world scientific collaboration: Authors, institutions, and countries , 2012, J. Assoc. Inf. Sci. Technol..

[23]  Michael Schreiber.  A case study of the modified Hirsch index hm accounting for multiple coauthors , 2009, J. Assoc. Inf. Sci. Technol..

[24]  Peder Olesen Larsen,et al.  Comparisons of results of publication counting using different methods , 2008, Scientometrics.

[25]  Tove Faber Frandsen,et al.  What is in a name? Credit assignment practices in different disciplines , 2010, J. Informetrics.

[26]  Peder Olesen Larsen,et al.  Publication, cooperation and productivity measures in scientific research , 2007, Scientometrics.

[27]  Loet Leydesdorff,et al.  Scopus's Source Normalized Impact per Paper (SNIP) versus a Journal Impact Factor based on Fractional Counting of Citations , 2010, J. Assoc. Inf. Sci. Technol..

[28]  Duncan Lindsey,et al.  Production and Citation Measures in the Sociology of Science: The Problem of Multiple Authorship , 1980 .

[29]  Ludo Waltman,et al.  On the calculation of percentile-based bibliometric indicators , 2012, J. Assoc. Inf. Sci. Technol..

[30]  Anthony F. J. van Raan,et al.  Citation Analysis May Severely Underestimate the Impact of Clinical Research as Compared to Basic Research , 2012, PloS one.

[31]  Henk F. Moed,et al.  Citation Analysis in Research Evaluation , 1899 .

[32]  Henk F. Moed,et al.  The research guarantors of scientific papers and the output counting: a promising new approach , 2013, Scientometrics.

[33]  Loet Leydesdorff,et al.  The operationalization of “fields” as WoS subject categories (WCs) in evaluative bibliometrics: The cases of “library and information science” and “science & technology studies” , 2014, J. Assoc. Inf. Sci. Technol..

[34]  T. Keats,et al.  On multiple authorship. , 1996, Skeletal radiology.

[35]  Mu-Hsuan Huang,et al.  The influences of counting methods on university rankings based on paper count and citation count , 2013, J. Informetrics.

[36]  Michael Schreiber,et al.  A modification of the h-index: The hm-index accounts for multi-authored manuscripts , 2008, J. Informetrics.

[37]  Benjamin F. Jones,et al.  Supporting Online Material Materials and Methods Figs. S1 to S3 References the Increasing Dominance of Teams in Production of Knowledge , 2022 .

[38]  Vincent Larivière,et al.  Team size matters: Collaboration and scientific impact since 1900 , 2014, J. Assoc. Inf. Sci. Technol..

[39]  Javier Ruiz-Castillo,et al.  Sub-Field Normalization in the Multiplicative Case: High- and Low-Impact Citation Indicators , 2011 .

[40]  Plergiorgio Strata,et al.  Citation analysis , 1995, Nature.

[41]  Thed N. van Leeuwen,et al.  The Leiden ranking 2011/2012: Data collection, indicators, and interpretation , 2012, J. Assoc. Inf. Sci. Technol..