Search Results
Abstract
Recent Swedish publication-based doctoral dissertations by medical practitioners contained an average of four published papers and one manuscript per theses. The average number of authors per paper was four. The candidate was the first author on 83% of papers indicating that the same paper was not used to support several theses. 82% of the candidates had completed their specialist training: 24% of these were women; surgeons were the biggest single group. The average age in years was: surgeons 40 (34–48); non-surgeons 41 (34–49); and 35 (32–36) for those who had just completed their basic post-qualification registration. These findings are in keeping with the Swedish tradition of scientific and evidence based medicine.
Abstract
Citation patterns of 400 very highly cited scientific papers are identified and the relationship of citation patterns to literature aging rates is investigated. Standardized citation counts for 1972 through 1980 are used as variables in a cluster analysis which groups papers with similar citation patterns and a discriminant analysis is used to refine the descriptions of clusters and to confirm the results. Among highly cited papers published in 1972, two basic citation patterns are identified: one group is highly cited in the first years following publication and declines in citedness thereafter; the second group reaches its citation peak in the sixth year following publication and declines in citedness in the seventh, eighth, and ninth years of the series. Both groups show general evidence of aging.Price's suggestion that less highly cited papers age more rapidly than more highly cited papers is confirmed.
Abstract
Analysis of the growth of radio and X-ray astronomy in the 1960s suggests that future reductions in the size of entering cohorts of new doctorates in astronomy may lengthen the time needed to exploit future innovations, discoveries or breakthroughs. This may well lead to slower rates of advancement in astronomical knowledge. Most scientists making up the early growth of these two problem areas hadrecently earned their Ph. D's, and, it was found, the probability of initiating research in radio or X-ray astronomy declined with the age of the scientist. Since smaller entering cohorts of new scientists would imply an overall aging of the astronomical community, the rate at which scientists will move in to exploit future innovations will probably be slower than during the periods of peak growth in the 1960s.
Abstract
Median age difference (D) is obtained by subtracting median value of the age distribution of references of a scientific paper from citing half life of the journal that published it. Such an indicator can be related to the state of knowledge of research groups and can show some interesting properties: 1) it must be related with the incorporation of information pieces in an informal way, say the rate of self-citations; 2) it must follow the natural tendency of the groups towards a progressively updated state of knowledge, and 3) more productive groups will tend to use more recent information. These natural hypotheses have been investigated using a medium sized Spanish institution devoted to Food Research as a case study. Scientific output comprised 439 papers published in SCI journals between 1999 and 2004 by 16 research teams. Their 14,617 references were analyzed. Variables studied were number of published papers by every team, number of authors per paper, number of references per paper, type of documents cited, self citation rate and chronological range of reference lists. Number of authors per paper ranged between 1 and 15. The most frequent value (N = 128) was 3 authors. Average number of authors per paper is 4.03 (SD = 1.74). Mean number of references per paper (including review papers) is 33.3 (SD= 17.39) with slight differences between the groups. Mean self-citation rate was 13.72 % (SD = 11.7). The greatest chronological range was 119 years; half of all ranges was 30 years and the general mean for this variable was 33.34 years (SD = 16.34). D values were associated with self-citation rate and a negative relationship between D and chronological range of references was also found. Nevertheless, correlation figures were too small to reach sound conclusions about the effect of these variables. Number of references per paper, number of contributing authors and number of papers published by each team were not associated with D. D values can discriminate between groups managing updated information and delayed research teams. Publication delay affects D figures. Discontinuity of research lines, heterogeneity of research fields and the short time lapse studied could have some influence on the results of the study. It is suggested that a great coverage is needed to evaluate properly D figures as indicators of information update of research groups.
Abstract
This paper proves two regularities that where found in the paper (Larivière et al. (2007). Long-term patterns in the aging of the scientific literature, 1900–2004. In Proceedings of ISSI 2007. CSIC, Madrid, Spain, pp. 449–456.). The first is that the mean as well as the median reference age increases in time. The second is that the Price Index decreases in time. Using an exponential literature growth model we prove both regularities. Hence we show that the two results do not have a special informetric reason but that they are just a mathematical consequence of a widely accepted simple literature growth model.
. Egghe , L. Rousseau , R. 2000 The influence of publication delays on the observed ageing distribution of scientific literature Journal of the American Society for Information
Publishing Co. Pte. Ltd. Singapore, Philadelphia . Burrell , Q. L. 2002 Modelling citation age data: Simple graphical methods from reliability theory
Abstract
This article presents an exploratory analysis of publication delays in the science field. Publication delay is defined as the time period between submission and publication of an article for a scientific journal. We obtained a first indication that these delays are longer with regard to journals in the fields of mathematics and technical sciences than they are in other fields of science. We suggest the use of data on publication delays in the analysis of the effects of electronic publishing on reference/citation patterns. A preliminary analysis on a small sample suggests that—under rather strict assumptions—the cited half-life of references may be reduced with a factor of about 2 if publication delays decrease radically.
