Progressive nucleation mechanism for the growth behavior of items and its application to cumulative papers and citations of individual authors

A general expression based on the concepts of the progressive nucleation mechanism is proposed in the form [Formula: see text] to describe the growth behavior of items in an individual system and a collective of systems. In the above relation, α(t) is the ratio of items N(t) at time t to the maximum number C of possible items for the system, Θ is the corresponding time constant and q is the exponent. The above relation is then used to analyze: (1) the growth behavior of cumulative number N(t) of papers published by individual authors and cumulative citations L(t) of N(t) papers of an author as a function of citation duration t, and (2) the relationship between cumulative citations L(t) of papers and cumulative number N(t) of papers. The proposed approach predicts that: (1) the fraction of items produced by successive systems is additive, (2) the cumulative fraction α(sum)(t) of maximum number of sites is the sum of contributions of fractions of maximum number of items produced by different systems, and (3) the values of time constants Θ and exponent q increase with the addition of fraction of items produced by subsequent systems, but their values are the lowest for individual systems. The approach is applied to explain the growth behavior of cumulative N(t) papers and L(t) citations of four selected Polish professors.     

Citation life cycles of ten citation classics

Not all highly cited papers have the same citation life cycle curves, i.e. curves of frequency of citations received vs. time. The citation life of ten randomly selected Citation Classics, five in medicine and five in biochemistry, are studied longitudinally in time and compared with a random sample of ten non-classics of the same cohort. There are pronounced differences in the life cycle curves; two distinct types are suggested. Type A, comprised of both high and low cited papers in both fields, has an early peak of citation rate and may be approximated by a bilinear cumulative citation curve with a break at six years of age, when three quarters of the total number of citations have occurred. Type B, in this study comprised of extremely highly cited methodological Citation Classics, exhibit a constant or slowly accelerating growth rate with a vigorous citation life extending over the entire period studied and typically one third or less of the total citations accumulated at six years of age.     

The relevance of short communication in scholarly journals: An empirical study

This study aims to examine whether rapid communications exert more influence/impact on subsequent research. Citation analysis of Short Communications (SCs) and Main Articles (MAs) from 1983 and 1990 for 5 high impact biomedical journals was carried out for a five year period following publication. The mean citations cumulated for the five year period showed no consistent trend. Some journals showed more citations for SCs while some showed more for MAs. The mean citations (range) for SCs and MAs for the 1983 and 1990 papers respectively were as follows:Gene: 14.13 (0-61) and 38.79 (0-677), 9.73 (0-93) and 13.17 (0-44);Journal of Clinical Investigation (JCI): 79.77 (3-202) and 27.52 (0-86), 50.52 (0-254) and 33.53 (0-151);Journal of Experimental Medicine (JEM): 39.80 (0-200) and 49.20 (0-403), 47.26 (0-258) and 50.27 (0-173); andJournal of Biological Chemistry (JBC); 36.21 (0-380) and 19.67 (0-53), 37.19 (0-273) and 26.84 (0-185). SCs ofJournal of Cell Biology (JCB) had a mean citation of 25.84 per article with a range of 0-98, while the MAs had a mean citation of 33.13 with the range 4-122 during 1983-87. The citation peak was seen about three years after publication for all the journals during both the periods. The mean cumulative citations showed a progressive increase over the five years for both types of papers, in all journals and for both the 5 year periods. The initial differences observed persisted even four years after the year of publication. No significant differences were observed in the distribution of the cumulative 5 year citations between the SCs and MAs. An index of speed of citation per article showed no substantial differences between SCs and MAs with MAs showing an edge over SCs. Both MAs and SCs of all the journals showed nearly same average time per citation per article further confirming that the SCs do not enjoy the advantage of speedier citation. The results show that the generally perceived feeling of SCs getting cited more frequently and faster does not appear to be valid. Hence, the practice of publishing SCs on a priority basis is perhaps not warranted.     

Sustained impact of publications of C.V. Raman

C.V. Raman is being acknowledged by worldwide physics community for his classic works. The present study has made an effort to analyze how much impact in number of citation receiving for his publications. Of course, there was a lack of tools for such a study some years back. The study has limited to the database Science Citation Index for the period 1982–2005. The noteworthy results are: One third of his research papers have been cited at least once; The research papers published during 1918–1940 could make remarkable impact; Three of his papers have shown an upward growth in number of citations receiving; The total citations to papers of age 46 and 54 as on the year 1982 accounted for more than 50 per cent of the total citations received; Research works in the ‘Acoustics’ area have been cited more than any other area of his works; Eponymal citations are to be explored and analysed to understand the real impact of his works.     

A longitudinal analysis of citation distribution breadth for Chinese scholars

Over the past 30 years, the research behavior of Chinese scholars has continually evolved. This paper studied the citing behavior of Chinese scholars by employing three indicators of citation concentration from the perspective of citation breadth analysis. All the citations from 2,338,033 papers from the Chinese Citation Database (1979–2008) covering four disciplines—Chemistry; Clinical Medicine; Library, Information and Archival Science; and Chinese Literature and World Literature—were analyzed. Empirical results show a general weakening tendency towards citation concentration: (1) decreasing percentage of uncited published papers within a given year; (2) a higher percentage of papers required to account for the same proportion of citation than before; and (3) the steady decline in the Herfindahl-Hirschman index (HHI) of citation distribution. All three measures indicate a decline in citing concentration or an increase in citation breadth. This phenomenon may be the result of increased access to materials, perhaps because of the ease with which scholarly materials can be accessed through the Internet.     

Use of bibliometric information to assist research policy making. A comparison of publication and citation profiles of Full and Associate Professors at a School of Chemistry in Uruguay

Summary Publication and citation profiles of Full and Associate Professors at the School of Chemistry of the Universidad de la República in Uruguay were investigated. The groups do not exhibit markedly different age averages. However, the average time since they started publishing, as well as other characteristics of their publication records, like productivity or citations, set them apart. From the point of view of both the number of papers per author and per year of activity, on one side, and of the number of citations per year of activity, on the other, the group of Full Professors has statistically significant larger averages than the Associate Professors. The impact of self-citations, multi-authorship and internationalization of the publications were analyzed within the two groups and shown to have no excessive or predictable influence on those parameters, except in the case of few (≤ 2) or many (>8) authors. It is suggested in this paper that these two indicators, number of papers per author per production year and number of citations per production year, combined in a plot allowing a bidimensional ranking of the individuals in the groups, may be used profitably as one of the components in the development of a policy toward promotion of Associate Professors. The analysis showed also that the quotient of citations received to number of papers published, even when derived from actual citation data of the scientists without involving the impact factors of the journals in which they publish, are not good parameters to use for that purpose, essentially because there is a reduction in the information content of the indicator with respect to those described before.     

Citation time window choice for research impact evaluation

This paper aims to inform choice of citation time window for research evaluation, by answering three questions: (1) How accurate is it to use citation counts in short time windows to approximate total citations? (2) How does citation ageing vary by research fields, document types, publication months, and total citations? (3) Can field normalization improve the accuracy of using short citation time windows? We investigate the 31-year life time non-self-citation processes of all Thomson Reuters Web of Science journal papers published in 1980. The correlation between non-self-citation counts in each time window and total non-self-citations in all 31 years is calculated, and it is lower for more highly cited papers than less highly cited ones. There are significant differences in citation ageing between different research fields, document types, total citation counts, and publication months. However, the within group differences are more striking; many papers in the slowest ageing field may still age faster than many papers in the fastest ageing field. Furthermore, field normalization cannot improve the accuracy of using short citation time windows. Implications and recommendations for choosing adequate citation time windows are discussed.     

Research performance of Turkish astronomers in the period of 1980–2010

We investigated the development of astronomy and astrophysics research productivity in Turkey in terms of publication output and their impacts as reflected in the science citation index for the period 1980–2010. Our study involves 838 refereed publications, including 801 articles, 16 letters, 15 reviews, and six research notes. The number of papers were prominently increased after 2000 and the average number of papers per researcher is calculated as 0.89. Total number of received citations for 838 papers is 6938, while number of citations per papers is approximately 8.3 in 30 years. Publication performance of Turkish astronomers and astrophysicists was compared with those of seven countries that have similar gross domestic expenditures on research and development, and members of organization for economic co-operation and development. Our study reveals that the output of astronomy and astrophysics research in Turkey has gradually increased over the years.     

Citation frequency: A biased measure of research impact significantly influenced by the geographical origin of research articles

Context. The use of citation frequency and impact factor as measures of research quality and journal prestige is being criticized. Citation frequency is augmented by self-citation and for most journals the majority of citations originate from a minority of papers. We hypothesized that citation frequency is also associated with the geographical origin of the research publication. Objective. We determined whether citations originate more frequently from institutes that are located in the same country as the authors of the cited publication than would be expected by chance. Design. We screened citations referring to 1200 cardiovascular publications in the 7 years following their publication. For the 1200 citation recipient publications we documented the country where the research originated (9 countries/regions) and the total number of received citations. For a selection of 8864 citation donor papers we registered the country/region where the citing paper originated. Results. Self-citation was common in cardiovascular journals (n = 1534, 17.8%). After exclusion of self-citation, however, the number of citations that originated from the same country as the author of the citation recipient was found to be on average 31.6% higher than would be expected by chance (p<0.01 for all countries/regions). In absolute numbers, nation oriented citation bias was most pronounced in the USA, the country with the largest research output (p<0.001). Conclusion. Citation frequency was significantly augmented by nation oriented citation bias. This nation oriented citation behaviour seems to mainly influence the cumulative citation number for papers originating from the countries with a larger research output.     

A bibliometric analysis of research related to ocean circulation

This study is a bibliometric analysis on ocean circulation-related research for the period 1991–2005. Selected documents included “ocean circulation, sea circulation, seas circulation, marine circulation, and circulation ocean” as a part of the title, abstract or keywords. Analyzed parameters included the document type, the article output, the article distribution in journals, the publication activity of countries, and institutes and the authorship. An indicator, citation per publication (CPP) was applied to evaluate the scientific impact of a publication. The relationship between cumulative articles and the year was modeled. Three dominant categories were picked out, and their output increase was modeled. The USA was found to be leading the research with 47% share of total articles, with a CPP up to 5.9. Woods Hole Oceanography Institute in the USA was the most productive institute with a CPP of 6.8. In the citation analysis, a 5th year citation mode was found. A paper life model was applied to compare the cumulative citations increasing rates of different years.     

The citation impact of social sciences and humanities upon patentable technology

This paper examines the citation impact of papers published in scientific-scholarly journals upon patentable technology, as reflected in examiner- or inventor-given references in granted patents. It analyses data created by SCImago Research Group, linking PATSTAT’s scientific non-patent references (SNPRs) to source documents indexed in Scopus. The frequency of patent citations to journal papers is calculated per discipline, year, institutional sector, journal subject category, and for “top” journals. PATSTAT/Scopus-based statistics are compared to those derived from Web of Science/USPTO linkage. A detailed assessment is presented of the technological impact of research publications in social sciences and humanities (SSH). Several subject fields perform well in terms of the number of citations from patents, especially Library and Information Science, Language and Linguistics, Education, and Law, but many of the most cited journals find themselves in the interface between SSH and biomedical or natural sciences. Analyses of the titles of citing patents and cited papers are presented that shed light upon the cognitive content of patent citations. It is proposed to develop more advanced indicators of citation impact of papers upon patents, and ways to combine citation counts with citation content and context analysis.

     

The highly cited papers of professors as an indicator of a research group's scientific performance

In the first part of the paper the citations in 1986 and 1987 of 3938 papers published in 1985 by 324 research groups in the faculties of science and of medicine of eight universities in the Netherlands are analyzed. Because of the large statistical spread of (1) the number of short-term citations of papers cited equally frequently over a long period, and (2) the number of citations over a long period of papers by the same author, short-term citation scores appear to be an unreliable indicator of a research group's contribution to science. In the second part of the paper an alternative approach is presented, based on a subdivision of the 3938 papers in papers authored by professors with 0–2, 3–8, or 9 highly cited papers (HCPs, 25 citations) to their name. Very large citation score differences were found for the three categories. For example: for papers first-authored by a professor, the average number of citations per person in 1986 and 1987 for 1985 papers was for 161 professors with 9 HCPs a factor 14 larger than for 575 professors with only 0–2 HCPs; for papers co-authored by professors, this factor was 6.6. These findings justify the conclusion that the number of HCPs scored by the professors (and other senior scientists) during their entire career is a much more reliable predictor of the performance of a research group than the number of short-term citations of the articles published by the group within a short period. A research group's contribution to science is primarily determined by the individual scientifictalents of its members.     

Positive and negative aspects of citation indices and journal impact factors

The Hirsch citation index h is nowadays the most frequently used numerical indicator for the performance of scientists as reflected in their output and in the reaction of the scientific community reflected in citations of individual contributions. A few of the possible improvements of h are briefly reviewed. Garfield??s journal impact factor (IF) characterizes the reaction of the scientific community to publications in journals, reflected in citations of all papers published in any given journal during the preceding 2?years, and normalized against all citable articles during the same period. Again, a few of the possible improvements or supplements of IF are briefly reviewed, including the journal-h index proposed by Braun, Gl?nzel, and Schubert. Ascribing higher weighting factors to citations of individual papers proportionally to IF is considered to be a misuse of useful numerical indices based on citations. At most, one could turn this argument on its head and one can find reasons to ascribe an inverse proportionality relative to IF for individual citations: if a paper is considered worthy to be cited even if it was published in a low-IF journal, that citation ought to be worth more than if the citation would have been from a higher-impact journal. A weight factor reflecting the prestige of the citing author(s) may also be considered.     

The effect of document types and sizes on the scaling relationship between citations and co-authorship patterns in management journals

The aim of this paper is to explore the power-law relationship between citation-based performance (CBP) and co-authorship patterns for papers in management journals by analyzing its behavior according to the type of documents (articles and reviews) and the number of pages of documents. We analyzed 36,241 papers that received 239,172 citations. The scaling exponent of CBP for article papers was larger than for reviews. Citations to articles increased 2^1.67 or 3.18 times each time the number of article papers published in a year in management journals doubled. The citations to reviews increased 2^1.29 or 2.45 times each time the number of reviews published in a year in management journals doubled. The scaling exponent for the power-law relationship of citation-based performance according to number of pages of papers was 1.44 ± 0.05 for articles and 1.25 ± 0.05 for reviews. The citations to articles increased faster than citation to reviews. The scaling exponent for the power-law of citation-based performance to co-authored articles was higher than single-authored articles. For reviews the scaling exponent was the same for the relationship between citation based performance and the number of reviews. Citations increased faster in single authored reviews than co-authored reviews.     

Early citation counts correlate with accumulated impact

Summary The present paper addresses the objective of developing forward indicators of research performance using bibliometric information on the UK science base. Most research indicators rely primarily on historical time series relating to inputs to, activity within and outputs from the research system. Policy makers wish to be able to monitor changing research profiles in a more timely fashion, the better to determine where new investment is having the greatest effect. Initial (e.g. 12 months from publication) citation counts might be useful as a forward indicator of the long-term (e.g. 10 years from publication) quality of research publications, but - although there is literature on citation-time functions - no study to evaluate this specifically has been carried out by Thomson ISI or any other analysts. Here, I describe the outcomes of a preliminary study to explore these citation relationships, drawing on the UK National Citation Report held by Evidence Ltd under licence from Thomson ISI for OST policy use. Annual citation counts typically peak at around the third year after publication. I show that there is a statistically highly significant correlation between initial (years 1-2) and later (years 3-10) citations in six research categories across the life and physical sciences. The relationship holds over a wide range of initial citation counts. Papers that attract more than a definable but field dependent threshold of citations in the initial period after publication are usually among the top 1&percnt; (the most highly cited papers) for their field and year. Some papers may take off slowly but can later join the high impact group. It is important to recognise that the statistical relationship is applicable to groups of publications. The citation profiles of individual articles may be quite different. Nonetheless, it seems reasonable to conclude that leading indicators of research excellence could be developed. This initial study should now be extended across a wider range fields to test the initial outcomes: earlier papers suggest the model holds in economics. Additional statistical tests should be applied to explore and model the relationship between initial, later and total citation counts and thus to create a general tool for policy application.     

Driving experience,crashes and traffic citations of teenage beginning drivers

Teenagers were surveyed by telephone every 6 months from their freshman to senior high school years (N=911). Self-reported crash involvements and citations were examined for each teenager's first year of licensure and first 3500 miles driven. Based on survival analysis, the risk of a first crash during the first month of licensure (0.053) was substantially higher than during any of the next 11 months (mean risk per month: 0.025). The likelihood of a first citation during the first month of licensure (0.023) also was higher than during any of the subsequent 11 months (mean risk per month: 0.012). Similarly, when viewed as a function of cumulative miles driven, the risk of a first crash or citation was highest during the first 500 miles driven after licensure. Fewer parental restrictions (e.g. no nighttime curfew) and a lower grade point average (GPA) were associated with a higher crash risk. Male gender, a lower GPA and living in a rural area were associated with a higher citation rate.     

Follow-up study: on the working time budget of a university teacher. 45 years self-observation

Results from self-observation of the working time distribution of a university teacher for a period of 45 years (starting from the very beginning of his carrier till two years after retirement) are reported classified in (i) teaching; (ii) scientific; (iii) administrative, organizational, technical; (iv) social/other activities. For the whole period, the teaching take 19 %, scientific work—22 % and various kinds of administrative, organizational and technical activities—52 % of the overall working time. The latter varies within the limits of 6.1–14.5 h per calendar day (mean values for an year) and in average is 10 h per calendar day for the entire 45-years-period. The changes of the working time distribution and the working day duration during the years are shown. The time consumed in fulfillment of obligations as head of research institution and of university units is revealed. The data are accompanied with information for the growth of the scientific production of the observed person. It is appeared that the latter as well as the growth of the citations of his papers can be depicted by the well known exponential law describing the accelerated development of the science.