10.59987/ads/2014.1.23-29
The aim of this study was to characterize the scientific production of Italian Oral Surgery professionals by evaluating different bibliometric indices. The bibliometric evaluation was conducted on the Scopus Database upon all the Active Members joining three important Italian scientific societies in Oral Surgery (SIdCO, SIO, and SICOI). The scientific production was analysed by considering the number of total publications, number of total citations, h-index, and hc-index. Moreover, the overall sample was divided into two groups (Academics and Not Academics), according to the fact the professionals had or not a university position, and then into sub-groups according to the different career lengths. Statistical analyses were performed to compare the scientific productivity amongst groups. For all the considered parameters a lack of homogeneity between groups was reported, and significantly greater mean values were recorded for the Academics compared to the Not Academics Group. Moreover, the h-index values increased more regularly as the career length progressed than the hc-index values, even if the last seemed to be less variable. h- and hc-indices are both stable bibliometric parameters, but as the hc-index values are related not only to the number of citation but also to their age, it seems to be less influenced by the authors’ career length. Bibliometric analysis of the scientific production in dentistry may facilitate the recognition of factors that may further enhance research activity and clinical performance and be useful for a comparative assessment of authors or research groups in terms of quality and quantity of the scientific production.
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Annali di stomatologia
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Characterizing scientific production of Italian Oral Surgery professionals through evaluation of bibliometric indices
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A. Polimeni 
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scientific production
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Characterizing scientific production of Italian Oral Surgery professionals through evaluation of bibliometric indices
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                                                                                                  Original article



    Characterizing scientific production of Italian
    Oral Surgery professionals through evaluation
    of bibliometric indices




                                                                                                                   li
                                                                 na
    Stefano Tetè, MD, DDS1†                                 ues increased more regularly as the career length
    Vincenzo Luca Zizzari, DDS1                             progressed than the hc-index values, even if the




                                                               io
    Alessandro De Carlo, DDS1                               last seemed to be less variable. h- and hc-indices
    Felice Lorusso, DDS 1                                   are both stable bibliometric parameters, but as
    Marta Di Nicola, MD2                                    the hc-index values are related not only to the
    Adriano Piattelli, MD 1                                 number of citation but also to their age, it seems




                                                            az
    Enrico Gherlone, MD, DDS3                               to be less influenced by the authors’ career
    Antonella Polimeni, MD, DDS4                            length. Bibliometric analysis of the scientific pro-
                                                            duction in dentistry may facilitate the recognition
                                                            of factors that may further enhance research ac-




                                                         rn
    1 Department of Medical, Oral and Biotechnological      tivity and clinical performance and be useful for a
      Sciences, “G. D’Annunzio” University, Chieti          comparative assessment of authors or research
      Pescara, Italy                                        groups in terms of quality and quantity of the sci-
    2 Department of Biomedical Sciences,“G. D’Annun-        entific production.




                                                      te
      zio” University, Chieti Pescara, Italy
    3 Department of Oral Science, “Vita-Salute San Raf-     Key words: career length, contemporary h-index,
      faele” University, Milan, Italy                       h-index, oral surgery, scientific production.
                                                   In
    4 Department of Oral and Maxillo-facial Sciences,

      Sapienza University of Rome, Italy
                                                            Introduction

    Corresponding author:                                   Recently, scientific research in dentistry gained great
                                                ni
    Stefano Tetè                                            importance due to the technological innovation in ma-
    Department of Medical, Oral and Biotechnological        terials and techniques, which were also introduced in
    Sciences, “G. D’Annunzio” University                    this field, and not less important, in order to improve
    Via dei Vestini, 31                                     the quality of dental care. Nowadays, even more den-
                              o

    66100 Chieti, Italy                                     tal professionals are involved in dental research, not
    E-mail: tete@unich.it                                   only researchers with a University position. The diffu-
                          izi


                                                            sion also of national and international scientific soci-
                                                            eties improved the interest of the clinicians in dental
    Summary                                                 research, both in an indirect way by showing their in-
                                                            terest in meetings participation and in staying up to
           Ed




    The aim of this study was to characterize the sci-      date on innovations, and both directly, by conducting
    entific production of Italian Oral Surgery profes-      primary or clinical research. In order to evaluate the
    sionals by evaluating different bibliometric in-        quality and the impact on society of this scientific ac-
    dices. The bibliometric evaluation was conducted        tivity, many different bibliometric indices were intro-
    on the Scopus Database upon all the Active Mem-         duced (1). The bibliometric analysis conducted on a
    bers joining three important Italian scientific soci-   group of authors is important because it allows to
    C




    eties in Oral Surgery (SIdCO, SIO, and SICOI). The      monitor the scientific development in that specific re-
    scientific production was analysed by consider-         search field, to permit an efficient allocation of re-
CI




    ing the number of total publications, number of         search funds, to improve the research activity in a de-
    total citations, h-index, and hc-index. Moreover,       termined field, to reward structures that host “high
    the overall sample was divided into two groups          quality” researchers, and to verify the presence of in-
    (Academics and Not Academics), according to the         efficiencies (2).
    fact the professionals had or not a university po-      Characterizing the scientific production of a single au-
    sition, and then into sub-groups according to the       thor or of a group of professionals involved in scientific
©




    different career lengths. Statistical analyses were     and clinical research is currently a complex process,
    performed to compare the scientific productivity        which is not based on a standardized methodology,
    amongst groups. For all the considered parame-          and that often uses criteria not entirely satisfactory for
    ters a lack of homogeneity between groups was           both the researchers and institutions (3).
    reported, and significantly greater mean values         Nowadays, the bibliometric evaluation in the medical
    were recorded for the Academics compared to the         field is possible by consulting numerous databases
    Not Academics Group. Moreover, the h-index val-         on the World Wide Web, each offering search facili-

    Annali di Stomatologia 2014; V (1): 23-29                                                                      23
    S. Tetè et al.


    ties on a particular subject. The scientific research      lished a long time ago and brilliant young scientists
    posed many questions about what tools and which            who produced a large number of significant publica-
    database is best to use and what are their features,       tions but that nowadays have a small number of im-
    even if a common idea has yet to be achieved (4).          portant papers due to the time constraint, and the age
    Evaluation of different bibliometric indices is one of     of the cites that would allow to identify scientists




                                                                                                                         li
    the best known methods for analyzing the entire sci-       whose contributions are still influential even if they
    entific production of an author or group of authors in     were published a long time ago.




                                                                    na
    order to detect the historical development, the quanti-    In fact, the h-index does not decline with the passing
    tative amount and the qualitative impact of scientific     of time, and likely an author may maintain unchanged
    studies. This method turns out to be at the same time      its h-index value even though he may not have any
    also the most criticized, because of the many vari-        published scientific articles in recent (12, 13). Differ-




                                                                  io
    ables that may be included in this evaluation (5).         ently, the contemporary h-index, by assigning a dif-
    For example, the evaluation of the absolute number         ferent weight to the most recent publications com-
    of publications or citations often does not allow to       pared to older ones, favors the authors with a sub-




                                                               az
    evaluate in a proper way the entire research activity      stantial recent scientific production respect to not
    of an author, and often it is not useful to compare two    more “scientifically active” researchers (1, 14, 15).
    authors. Therefore, many other indicators were intro-      The aim of this study was to characterize the scientif-
    duced and are currently used in order to perform           ic production of Italian Oral Surgery professionals by




                                                            rn
    these evaluations (6).                                     evaluating different bibliometric indices, and to com-
    One of the most popular and useful index for the           pare the performance of h-index and hc-index in mir-
    evaluation of an author’s scientific production is the     roring the scientific production distribution among re-
    h-index, suggested by Hirsch J., and its variables.        searchers with different career lengths.




                                                         te
    The h-index is defined as the highest number of pa-
    pers of a scientist that have been cited h or more         Materials and methods
    times (7).
    The h-index is simple to calculate and allows in a         Experimental parameters
                                                      In
    synthetic way to determine both the quantity and the
    quality of an author’s scientific production, based on     All data were found and recorded from January 7 to
    both the number of publications and the number of ci-      January 19, 2013. For each author were considered
    tations each publication received. The total number of     publications and related citations indexed in Sci-
    publications give back, by scientific insight, the pro-    Verse® Scopus database until 31 December 2012; on
                                         ni

    duction of a specific author, while the number of cita-    the other hand, were excluded from the calculation at
    tions made from the scientific community, give the         the time of data acquisition, articles published from
    opportunity to verify the best researchers, works and      January 1, 2013 and 2013 citations of articles pub-
                            o

    institutions, as well as the most common areas of re-      lished until December 2012.
    search or interest, based on the assumption that the
                        izi


    most interesting scientific contributions are also those
    that are most frequently cited (6). From its introduc-     Selection of the study population
    tion, the h-index was already applied to several disci-
    plines, such as Physics, Biology, Biomedicine,             The list of Italian professionals involved in Oral
            Ed




    Healthcare, etc. (6).                                      Surgery was obtained by selecting the Active Mem-
    Many researchers pointed out some drawbacks of the         bers of the 3 most important Italian scientific societies
    h-index, related to several different variables which      in Oral Surgery, SIdCO (Italian Society of Oral
    influence the assessment of scientific output of a re-     Surgery, SIO (Italian Society of Osseointegration),
    searcher. Moreover once a paper has reached the            and SICOI (Italian Society of Oral Surgery and Im-
    number of citations which qualifies it for the core set,   plantology), downloadable online (http://www.sidcoin-
    C




    then further citations are irrelevant (7, 8).              forma.it/, http://www.sicoi.it/, http://www.osteointe-
    An other criticism could be that no other kind of pro-     grazione.it/, respectively). All researchers names
CI




    duction such as books, chapter in books or proceed-        were included in a Microsoft Excel file created ad
    ings are being considered, neither publications in         hoc. The overall population was firstly divided into
    journals that are not part of the database used for the    two different groups, depending on the member be-
    author’s search, no matter how many times they are         longing to a university setting or not, named Acade-
    cited (9, 10).                                             mics and Not Academics, respectively. The overall
    Many authors consider the h-index roughly influenced       sample was then further divided into sub-groups ac-
©




    by the career length, as its value is likely to increase   cording to the different career length, where the defi-
    linearly with time. A time related index was proposed      nition of career length of a researcher was used to
    by Sidiropoulos et al., the contemporary h-index (11).     identify the period since his first publication to 31 De-
    These authors investigated how this index could be         cember 2012. The sub-groups were obtained by di-
    adapted to take into account the age of the papers,        viding the Academics Group into tertiles according to
    thus differentiating between senior scientists that        their career length, and the Not Academics Group in-
    have received many of their cites due to papers pub-       to quartiles (Tab. 1).

    24                                                                             Annali di Stomatologia 2014; V (1): 23-29
    Scientific production of Italian Oral Surgeons


    Data collection                                                   searcher’s topics of interest, the scientific production
                                                                      of the author and the time period in which it was pro-
    The database chosen for the collection of data biblio-            duced, in order to enclose in the most faithful way as
    metric was SciVerse ® Scopus (www.scopus.com).                    possible the scientific production of the same author.
    The bibliometric data collection was performed by                 Total number of publications were calculated regard-




                                                                                                                                   li
    three operators with experience in the field of litera-           less of the type of all indexed publications on Scopus
    ture search. In accordance with the site instructions




                                                                        na
                                                                      (at example: proceddings, review, article, letters).
    to search for author, for each name in the “Author
    Search”, (http://www.scopus.com/search/form.url?dis-
    play=authorLookup&clear=t&origin=searchbasic&txGi                 Data recording and characterization
    d=4GSgDGaqqvp9pwfgYXjS7W8%3a3) the following                      of the scientific production




                                                                      io
    data have entered: surname, first names, and in sub-
    section “Subject Areas” have been checked items                   For each researcher, the following parameters were
    “Life Science” and “Health Science”. It was decided to            derived from the authors Scopus data: total number




                                                                   az
    include only the initials of the name to prevent possi-           of publications, total number of citations, and h-index.
    ble loss of data due to the fact that some publica-               The corresponding hc-index was calculated using the
    tions, not showing the name of the author, cannot be              ABILITANVUR v0.9, 2012-11-15© software (Vincen-
    traced by the system. After viewing the search re-                zo Della Mea, University of Udine http://mitel.dimi.uni-




                                                                rn
    sults, it was proceeded to click on the “Show Profile             ud.it/varia/abilitanvur/), through the achievement of a
    Matches with One Document”, where present, to in-                 file ad hoc (.csv) where every single publication from
    clude in the calculation of the total profiles with a sin-        each author were reported including the data of publi-
    gle publication that were not shown in the first in-              cation and the number of citation in the format




                                                             te
    stance.                                                           (year,citation). All this parameters were inserted into
    In cases of same name and surname or mismatch of                  spreadsheet Office Excel 2007 (Microsoft Corpora-
    affiliations among the results, profiles that were not            tion. Redmont, Washington State) containing the au-
    attributable to the contact examined were excluded at
    the discretion of operators according to the re-
                                                          In          thors and each numeric value was formatted to three
                                                                      decimal fraction (Tab. 2).



    Table 1. Groups definition and numerosity. (x = career length is defined as the number of years since each professional’s
                                                ni
    first publication to December 31st 2012.)

    Groups                  Definitions                                                                                   Sample size
                              o

    Total sample            Active Members having at least one scientific publication indexed on Scopus                   n=214
    Academics               Active Members of the Italian scientific societies analyzed                                   n=58
                          izi


                            belonging to a university setting
        10≤x≤23             Authors career length comprised between 10 and 23 yrs                                         n=19
        24≤x≤29             Authors career length comprised between 24 and 29 yrs                                         n=22
        30≤x≤43             Authors career length comprised between 30 and 43 yrs                                         n=17
              Ed




    Not Academic            Active Members of the Italian scientific societies analyzed                                   n=156
                            not belonging to a university setting
        1≤x≤7               Authors career length comprised between 1 and 7 yrs                                           n=40
        8≤x≤16              Authors career length comprised between 8 and 16 yrs                                          n=44
        17≤x≤28             Authors career length comprised between 17 and 28 yrs                                         n=38
        29≤x≤50             Authors career length comprised between 29 and 50 yrs                                         n=34
    C
CI




    Table 2. Indicators formulae used in the study

    Indicator                Description                                                  Formula
    Total Publication        Total number of pubblication for each author                 Doc1 + doc2 +…..docn
                             found on Scopus until December 31st 2012
©




    Total Citations          Total number of citation for each author found on            Cit1 + cit2 +…. citn
                             Sopus database until December 31st 2012
    h-index                  Hirsh-index resulted from the author’s account               Index h: h of his Np have h citations each
                             of Scopus database                                           and the other (Np - h) papers have ≤ hc
    hc-index                 Contemporary H index variable of Hirsh-index                 S(I,t)=4/(t-t1+1) * C(I,T), t >=t1
                             calculated from the Abilitanvur online software


    Annali di Stomatologia 2014; V (1): 23-29                                                                                      25
    S. Tetè et al.


    Statistical analysis                                        Academics. Data regarding the different sub-groups
                                                                were reported in Tables 4 and 5. In particular, it could
    Researchers showing 0 publication were excluded             be noted that the h- and hc-index did not have a con-
    from the statistical analysis. All the analysis were con-   tinuous increase along with the progression of an au-
    ducted on the total population sample and for each          thor career, as with the increasing number of total




                                                                                                                          li
    group considered. Data were processed to calculate          publications and citations. As for the median h-index
    median, interquartile range (IR), coefficient of varia-     in the Academics group, it was found to remain stable




                                                                     na
    tion, and range (R) of the following: the number of to-     when considering the researchers with a career
    tal publications, number of total citations, h-index, and   length of more than 24 years, while a peak of hc-in-
    hc-index. Kurtosis test was performed in order to as-       dex could be recorded for the subgroup with a career
    sess data distribution. Data were then analysed by the      length between 24 and 29 years. As for the Not Acad-




                                                                   io
    Wilcoxon test, in order to check whether there was          emics group, a slight gradual increase of the h-index
    statistically significant difference between the groups,    median values was observed, while the highest hc-in-
    using the add-in for Microsoft Excel, PHStat2 (Pren-        dex median value was recorded for the researchers




                                                                az
    tice Hall, Inc., Pearson Education). Each statistic test    with a long career.
    was considered true when the probability value (p-val-
    ue), compared with the desired significance level of
    our test (p < 0.05), was smaller.                           Discussion




                                                             rn
                                                                Approaching a bibliometric analysis, the crucial initial
    Results                                                     point is the choice of the best database where finding
                                                                data with minor risks to have bias or mistakes for au-




                                                          te
    Characterization and impact                                 thors’ scientific production. Among the more known
    of scientific production                                    databases for bibliometric evaluation, we considered
                                                                SciVerse ® Scopus was used for this study. In the
    In this study, a total of 260 Active Members belonging      opinion of the authors, Scopus appeared to be the
                                                       In
    to the three main Italian scientific societies involved     most complete database with the largest bibliography
    in Oral Surgery, SIdCO, SIO, and SICOI, were select-        of abstracts and citations in the scientific literature.
    ed. Between all the Active Members considered,              Scopus indexes nearly 18,000 journal titles (mostly
    83,4% of them (n=214) had at least one scientific           peer-reviewed journals) in the scientific, medical,
    publication indexed on Scopus database, and were            technical, humanities and social sciences, published
                                         ni

    considered for the bibliometric analysis.                   from more than 5,000 publishers, and is regularly up-
    The overall data, related to the total population,          dated (16). Among the most important features, Sco-
    proved the scientific production distribution of those      pus citation can easily derive the h-Index of the au-
                            o

    professionals to be rather uneven, by considering the       thors allowing to make the citation analysis of authors
    median value of 11 (IR: 3 - 34). Also according the         and publications (through the Citation Tracker) and to
                        izi


    number of citations per researcher, a median of 4 (IR:      carry out the analysis of the profile of the authors and
    9 - 191.75) was recorded, revealing a high variability      affiliations. However, it has the considerable limit that
    between the overall sample. Similarly, the median h-        it calculates the h-index without taking into considera-
    index was 4 (IR: 1-7), while the median hc-index was        tion papers published prior to 1996; in this way au-
            Ed




    3 (IR: 1 - 6).                                              thors with a scientific production more limited in time
    By considering the overall population, the scientific       have an advantage (2).
    production in the last ten years represented about          Other databases were also evaluated before using
    68.95% compared to the total scientific publications        SciVerse® Scopus for this study. With regard to ISI
    of the samples (data not shown). All the Active Mem-        Web of Science, although easy to use because it in-
    bers were divided between the Academics and Not             corporates the calculation function h-index, it pos-
    C




    Academics Groups, as previously described. Among            sesses several “weak points”. First, the database in-
    the Active Members of the scientific society consid-        cludes only the journals that are listed in the Thom-
CI




    ered, the Not Academics (n=156) were more numer-            son Reuters (17). Consequently, the scientific pro-
    ous than the Academics (n=58).                              duction of an author may be severely underestimated
    In particular, the Academics showed a median value for      because of the absence of some publications. In ad-
    total number of publications significantly higher (36.5;    dition for the reasons set out above, in calculating the
    IR: 22.25 - 66.5) than Not Academics (6; IR: 2 - 20.25).    h-index of an author, all citations made in journals not
    As regards the other parameters considered, i.e. the        indexed in ISI Thomson Reuters database are ex-
©




    number of citations, the h-index and hc-index, it was       cluded, whereby the result does not respond to a pre-
    possible to notice a lack of homogeneity between the        cise mathematical calculation. Finally, from the cita-
    Academics and the Not Academics Groups, as de-              tions report are excluded all references showing even
    scribed in Table 3.                                         small errors in the formatting or writing.
    Furthermore, the distribution of the overall scientific     Also the databases which can be accessed for free,
    production among researchers with different career          as Medline and Google Scholar, have some limita-
    length was evaluated both for the Academics and Not         tions. Even if, Medline was found to be the database

    26                                                                              Annali di Stomatologia 2014; V (1): 23-29
                                                            ©
                                            Table 3. Characterization of the overall scientific production of the Active Members and comparison between the Academics and Not Academics Groups.

                                                                               Total publications                                    Total citations                                          h-index                                                 hc-index
                                            Group                 Total              Academics     Not               Total              Academics      Not             Total              Academics          Not           Total                  Academics          Not
                                                                               CI
                                                                  Sample                       C   Academics         Sample                            Academics       Sample                                Academics     Sample                                    Academics
                                            Median                11                 36.5          6                 59                 196            31              4                  7                  2             3                      6                  2
                                            Interquartile         3-34               22.25-66.5    2 – 20.25         9-191,75           70-541.75      4-112.75        1-7                4 – 11.75          1–5           1-6                    4 - 10             1–4
                                            range
                                            Coefficient           1,78               1,351         0,694             2,66               2,029          1,921           1,11               0,812              1,1           0,96                   0,654              1,004
                                            of variation
                                                                                                             Ed
                                            Range                 1-584              9 - 584       1 - 106           0-7187             2 - 7187       0 - 1487        0-41               1 - 41             0 - 22        0-23                   1 - 23             0 - 15




Annali di Stomatologia 2014; V (1): 23-29
                                            Table 4. Characterization of the Active Members with a University setting divided into tertiles according to their career length.
                                                                                                                                                                                                                                                                                       Scientific production of Italian Oral Surgeons




                                                                                                                                                                    Academics
                                                                                                                            izi
                                                                                 Total publications                                        Citations                                               h-index                                              hc-Index
                                            Group                      10 ≤ x ≤ 23     24 ≤ x ≤ 29      30 ≤ x ≤ 43
                                                                                                                                o
                                                                                                                          10 ≤ x ≤ 23     24 ≤ x ≤ 29       30 ≤ x ≤ 43      10 ≤ x ≤ 23       24 ≤ x ≤ 29       30 ≤ x ≤ 43       10 ≤ x ≤ 23         24 ≤ x ≤ 29       30 ≤ x ≤ 43
                                            Median                     21              39               59                122             199               225            6                   8                 8                 6                   7                 6
                                            Interquartile              14-41,5         25,5-62,5        36-105            42-303,5        80-703,5          80-590         4-8,5               6-14,5            5-12              4-8,5               4-12              4-10
                                                                                                                                                   ni
                                            range
                                            Coefficient                1,139           0,752            1,31              1,992           1,273             2,184          0,873               0,696             0,867             0,667               0,596             0,68
                                            of variation
                                            Range                      10-191          10-156           23-584            7-3179          56-2121           31-7187
                                                                                                                                                                    In     2-31                3-27              2-41              2-18                2-19              2-23


                                            Table 5. Characterization of the Active Members without a University setting divided into quartiles according to their career length.
                                                                                                                                                                       te
                                                                                                                                                             Not Academics

                                                                             Total publications                                       Citations                                                h-index                                                 hc-Index

                                            Group           1 ≤ x ≤ 7 8 ≤ x ≤ 16 17 ≤ x ≤ 28 29 ≤ x ≤ 50 1 ≤ x ≤ 7 8 ≤ x ≤ 16 17 ≤ x ≤ 28 29 ≤ x ≤ 50                  1 ≤ x ≤ 7 8 ≤ x ≤ 16 17 ≤ x ≤ 28 29 ≤ x ≤ 50 1 ≤ x ≤ 7 8 ≤ x ≤ 16 17 ≤ x ≤ 28 29 ≤ x ≤ 50
                                                                                                                                                                          rn
                                            Median          2            6             7           32            5           54           42            108,5          1           2,5             3             4             1           2,5             2                 3

                                            Interquartile   1-3          2,25-17,5     3-19        9,25-55       1-11,5      22-145       7-109         11,75-263,75 1-1,5         1-5,75          2-6           2-7,75        1-1         1-5             1-5            1-6
                                            range
                                                                                                                                                                             az
                                            Coefficient     1,72         1,491         1,427       0,791         1,847       1,136        1,947         1,355          0,901       0,792           1,135         0,855         0,852       0,761           1,052          0,835
                                            of variation

                                            Range           1,35         1-106         2-105       1-90          0-101       1-415        0-1487        0-1113         0-5         1-11            0-22          0-17          0-4         1-10            0-15           0-11
                                                                                                                                                                                io


  27
                                                                                                                                                                                  na
                                                                                                                                                                                                                                                                 li
    S. Tetè et al.


    which is updated with the greatest regularity and thus        a. The h-index is represented by a natural number,
    able to provide an overview of the most current scien-             usually belonging to a small set, which then has,
    tific production of an author, it dids not have a report           as they say in mathematical jargon, a low resolu-
    or a function that can take into account the citations of          tion, which is determined by a flattening of the
    each publication and therefore cannot allow the calcu-             values of h-index of researchers, which penalizes




                                                                                                                             li
    lation of the h-index and other indices for the assess-            those that have a high number of citations com-
    ment of the appreciation of a given publication (18).              pared to those who have less, making the gap be-




                                                                      na
    As well as other databases, Publish or Perish on                   tween them less noticeable.
    Google Scholar is not able to trace the entire scientif-      b. While some databases penalize “old” researchers,
    ic output of an author, even if studies showed that it             the h-index penalizes “young” researchers, as the
    is accurate enough to evaluate properly the scientific             more recently published papers are less likely to




                                                                    io
    productivity of an author. Indeed, this database                   be cited in other articles just because they did not
    seemed to have a higher coverage than the other                    have enough time to accumulate citations.
    with regard to citations to articles on book chapters         c. The h-index is a realistic way to assess the scien-




                                                                 az
    and conference proceedings, as well as journals in                 tific value of an author if its production is spread
    languages other than English, and seemed to have                   over 10 years. On the contrary, the h-index could
    good coverage for very dated publications. Publish or              be an advantage for those who have published
    Perish contains functions able to perform an analysis              extensively in the past but whose scientific pro-




                                                              rn
    of the scientific production of the author, including              duction in recent years has been reduced or even
    even the automatic calculation of various indices, in-             stopped because the older articles have had more
    cluding the h-index, the m-index, the g-index, the e-              time to be cited by others despite the interest of
    index, but it seemed to be less accurate than Scopus               the scientific production is expected to be very




                                                           te
    in discriminating researchers with similar surnames                low considering the scientific progress occurred at
    and names (1, 12).                                                 the same time.
    In the present study, by considering the overall popu-        d. In the computation-index there could also be a
    lation of Active Members joining the three most im-                massive loss of information, since by definition
                                                        In
    portant Italian scientific societies in Oral Surgery, a            the h-index equals the number (N) of articles that
    very heterogeneous sample could be recorded, as                    have received a number of citations greater than
    shown by the Kurtosis test and the coefficient of vari-            or equal to N. Items that have received a substan-
    ation.                                                             tial number of citations did not affect the h-index.
    Considering the total number of scientific publica-                To give an example, if an author has an h-index
                                           ni

    tions, the data showed that more than half of the pub-             of 5, it means that 5 of its articles have been cited
    lications have been produced in the last ten years.                each a number of times equal to 5 or more. In this
    This result confirms the validity of the Italian scientific        calculation the total number of citations is not
                             o

    research in the field of oral surgery and how this re-             considered, therefore if one or more of these arti-
    search has been increasing in recent years.                        cles has a very high number of citations, the final
                         izi


    As expected, the bibliometric analysis showed a sig-               value of the h-index does not change, and it may
    nificant difference in scientific production between the           be equal to the h-index of an author with a small-
    Not Academics group and the Academics Group of                     er number of citations.
    professionals belonging to the main scientific soci-          e. One of the most criticized aspects of h- index is the
            Ed




    eties of surgical specialties in dentistry, both in quali-         possible influence of self-citations. Self-citations do
    tative and quantitative terms. In fact, by analyzing the           have a great impact on the h-index, especially in
    distribution of all the analysed parameters, signifi-              the case of young scientists with a low h-index.
    cantly higher values could be detected in the Acade-          The hc-index is based on the normalization of cita-
    mics Group. In the Not Academics group, more than             tions based on the elapsed number of years since the
    20% of the researchers evaluated did not have any             paper has been published. It takes into consideration
    C




    scientific publication indexed in Scopus. This finding        the age of an article (19). A scientist, for example,
    can be explained by considering that a professional,          has a number of significant articles that produced a
CI




    unlike a university professor, have more difficulties in      large h-index, but recently he became rather inactive
    being engaged in scientific research.                         or was retired. Therefore, senior scientists, who still
    The h-index and hc-index values recorded suggest              keep their contributions, or brilliant young scientists,
    that the Italian scientific production in Oral Surgery        who are expected to contribute a large number of sig-
    presents points of excellence, although the median            nificant papers in the near future but now have only a
    values indicate the presence of few researchers with          small number of important articles due to the time
©




    scientific production quantitatively valid and continu-       elapsed, are not distinguished by the original h-index.
    ous in time.                                                  Both indices could have a high value, because they
    The h-index can detect the actual influence of an au-         showed a low coefficient of variation in an indepen-
    thor on the scientific community, irrespective of the         dent way from the groups considered.
    fact that he may have published individual articles of        The comparison between h-index and hc-index con-
    great success or many articles with low number of ci-         firmed how this variable reduced discrepancies in
    tations (4).                                                  evaluating the scientific production of a group of au-

    28                                                                                 Annali di Stomatologia 2014; V (1): 23-29
    Scientific production of Italian Oral Surgeons


    thor. Moreover, the h-index was found to gradually in-              5. Falagas ME, Pitsouni EI, Malietzis GA, Pappas G. Com-
    crease along with the number of publications and ci-                   parison of PubMed, Scopus, Web of Science, and Google
    tation in each group and to remain stable when con-                    Scholar: strengths and weaknesses. FASEB J 2008;22:338-
                                                                           342.
    sidering the researchers with longer career length.
                                                                        6. Alonso S, Cabrerizo FJ, Herrera-Viedma E, Herrera F. h-in-
    Otherwise, hc-index, for its nature, tends to vary less




                                                                                                                                         li
                                                                           dex: A Review Focused in its Variants,Computation and Stan-
    significantly as the professionals career gets longer,                 dardization for Different Scientic Fields. J Informetrics
    thus allowing to compare in a more equal way the sci-




                                                                           na
                                                                           2009;3:273-289.
    entific production of researchers with a different ca-              7. Hirsch J. An index to quantify an individual’s scientifc research
    reer length (2).                                                       out-put. Proceedings of the National Academy of Sciences
                                                                           2005;102:16569-16572.
                                                                        8. Patel VM, Ashrafian H, Ahmed K, Arora S, Jiwan S, Nichol-




                                                                         io
    Conclusions                                                            son JK, et al. How has healthcare research performance been
                                                                           assessed?: a systematic review. J R Soc Med 2011;104:251-
                                                                           261.
    It should be reported that the results of a bibliometric
                                                                        9. Schreiber M. Twenty Hirsch index variants and other indi-




                                                                      az
    analysis conducted on the basis of these indices,
                                                                           cators giving more or less preference to highly cited papers.
    though providing synthetic measurements, can not be                    Phys 2010;522:536-554.
    immediately translated into absolute qualitative as-               10. Kellner AW, Ponciano LC. H-index in the Brazilian Acade-
    sessments. In fact, the citation analysis, besides spe-                my of Sciences: comments and concerns. An Acad Bras
    cific considerations regarding reliability, availability




                                                                   rn
                                                                           Cienc 2008;80:771-781.
    and solidity of the data, was not able to fully assess             11. Sidiropoulos A, Katsaros D, Manolopoulos Y, Generalized
    the applied research, or career path a researcher in                   hirsch hindex for disclosing latent facts in citation networks.
    its entirety, but it can be used for an assessment for                 Scientometrics 2007;72:253-280.
                                                                       12. Bakkalbasi N, Bauer K, Glover J, Wang L. Three options for




                                                                te
    the comparative evaluation of different authors or re-
                                                                           citation tracking: Google Scholar, Scopus and Web of Sci-
    search groups.
                                                                           ence. Biomed Digit Libr 2006;29:3-7.
                                                                       13. Thompson DF, Callen EC, Nahata MC. Publication metrics
                                                                           and record of pharmacy practice chairs. Ann Pharma-
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    Annali di Stomatologia 2014; V (1): 23-29                                                                                            29
