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index which is independent of his/her age (Kosmulski 2009 ; Abt 2011 ), and (2) the accuracy of this index is the same as that of the h index (Abt 2011 ). These authors proposed that one can compare the publication activity of authors of different
Abstract
In this paper, I will argue that the process of ageing in scientific publications on the one hand, and the process of obsolescence and forgetting to which all kinds of phenomena, people and events are exposed on the other, develop with the same speed. Whereas in the literature on the subject it is stated that the speed of the ageing of scientific literature is exponential, it is shown that the decay from 'age 4' is best described by an inverse function, as was already brought to light in reference to forgetting of people and events as measured by the frequencies of calendar years in large text corpora. The empirical bases are SCI data as presented by Nakamoto and various files of reference data collected by the author. It is shown that the decay curve of the reference frequencies from 'age 4' backwards is independent of time.
paper, the result is statistically constant, as we shall see below. Let us call that index an a -index for “age independent”. After deriving the h -index, it takes about 10 s to derive the a -index. Analysis I used data
Abstract
A non-homogeneous birth process is used to describe the statistical properties of bibliometric citation processes. The model is analysed under special assumptions. Thelife-time distribution, special probabilities and mean value functions are used to characterize differences in the ageing structure of scientific literature, the change of citation impact in time and to analyse predictive aspects of reception processes. The results are applied to selected journals representing one field in science and social science each. The empirical part of the study is based on a 14-year citation history (papers published in 1978 and cited 1978–1991). An intimate, connection between impact and ageing cannot be observed. However, the ageing behaviour seems to be clearly influenced by field characteristics and by special document/journal types, such as letters and short communications.
Age likes some years
A case study for ages more prone to death
Summary
A person can die at any age. It is an omni-spoken common saying. Is it really true? Are all ages equally prone to die? Does there exist some predictable pattern that may conjecture the incidence of death? These are the questions that are attempted here in this article. Literature is replete with cohort dependant age distributions and pyramids that focus, and are adjusted, primarily for the living persons. The current article is using a cohort free group of people and focuses exclusively on age at death to rummage for some pattern in these ages. A statistical investigation is made of the life span of human beings of previous two centuries. The life span, or age, distribution is revealed to be a quadric modal in nature, refuting the prevailed myth that all ages are equally susceptible to death.
Abstract
The size and ageing of the Chilean scientific community was studied using as data the individuals actively engaged in research projects funded by the National Fund for Scientific and Technological Development (FONDECYT). Between 1982 and 1991, 4966 individuals participated at least once, either as responsible for the research or as qualified associate in one term of the funding period. From this population, 2765 persons can be considered further committed with scientific research. As for sex, about 30% of the researchers are women. Taking into account all the disciplines, and in addition to the fact that the size of the Chilean scientific community seems to be subcritical, the study reveals that the workforce has been ageing dangerously through the years. The number of young scientists becoming part of the scientific workforce is decreasing. Research in mathematics, physics and chemistry, although qualitatively competitive, relies only on an extremely small group of excellent scientists, situation which is seriously affecting the scientific capacity that the country needs. Biology, although with a higher number of individuals, exhibits a pattern of ageing which will also affects the possibilities to strengthen the scientific demands. The global context in which science develops, leads to a brain drain that Third World countries will have to overcome, implementing public policies to offer the support that young people require to nurture the scientific strength. Indigenous Ph. D. programs demand urgent attention of policy decision makers as well as from research universities which need to offer opportunities to substitute, when existing, their incompetent faculty.
Abstract
On the basis of the measured time-dependent distribution of references in recent scientific publications, we formulate a novel model on the ageing of recent scientific literature. The framework of this model is given by a basic set of mathematical expressions that allows us to understand and describe large-scale growth and ageing processes in science over a long period of time. In addition, a further and striking consequence results in a self- consistent way from our model. After the Scientific Revolution in 16th century Europe, the 'Scientific Evolution' begins, and the driving processes growth and ageing unavoidably lead - just as in our biological evolution - to a fractal differentiation of science. A fractal structure means a system build up with sub-systems characterised by a power-law size distribution. Such a distribution implies that there is no preference of size or scale. Often this phenomenon is regarded as a fingerprint of self-organisation. These findings are in agreement with earlier empirical findings concerning the clustering of scientific literature. Our observations reinforce the idea of science as a complex, largely self-organising 'cognitive eco-system'. They also refute Kuhn's paradigm model of scientific development.
different variables, such as professional rank and age, on authorship practices has also been explored in the literature, noting that scientists tend to sign more as last author and less often as first author as they get older (Gingras et al. 2008 ) and as
Abstract
Age effects in scientific production are a consolidated stylised fact in the literature. At the level of scientist productivity declines with age following a predictable pattern. The problem of the impact of age structure on scientific productivity at the level of institutes is much less explored. The paper examines evidence from the Italian National Research Council. The path of hiring of junior researchers along the history of the institution is reconstructed. We find that age structure has a depressing effect on productivity and derive policy implications. The dynamics of growth of research institutes is introduced as a promising research field.
Abstract
The time-course of average age of members of the Russian Academy of Sciences in the XVIII–XIX centuries was analyzed. A long-term trend of academician aging was found, with its extrapolation correctly predicting the average age of the recent academicians. Although the lifespan was increasing as well and its effect can statistically explain the most part (up to 80%) of variance in the average age, it was not the only cause. Furthermore, its effect might be indirect (i.e. the increasing average age was not simply due to a longer lifespan of elected members), since average membership span was slightly decreasing. At least a part of the trend was caused by a growth of competition for election since it was negatively correlaten with a contemporaneous number of members (at given lifespan and historical year). Comparison of three groups (full members, corresponding members and foreign members), differing in competition level, supports this suggestion. Besides the history of science, the results may be useful for dealing with the problem of growing age of the scientific establishment.
