Lotka's law
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Lotka's law,[1] named after Alfred J. Lotka, is one of a variety of special applications of Zipf's law. It describes the frequency of publication by authors in any given field. Let X be the number of publications, [math]\displaystyle{ Y }[/math] be the number of authors with [math]\displaystyle{ X }[/math] publications, and [math]\displaystyle{ k }[/math] be a constants depending on the specific field. Lotka's law states that [math]\displaystyle{ Y \propto X^{-k} }[/math].
In Lotka's original publication, he claimed [math]\displaystyle{ k=2 }[/math]. Subsequent research showed that [math]\displaystyle{ k }[/math] varies depending on the discipline.
Equivalently, Lotka's law can be stated as [math]\displaystyle{ Y' \propto X^{-(k-1)} }[/math], where [math]\displaystyle{ Y' }[/math] is the number of authors with at least [math]\displaystyle{ X }[/math] publications. Their equivalence can be proved by taking the derivative.
Example
Assume that n=2 in a discipline, then as the number of articles published increases, authors producing that many publications become less frequent. There are 1/4 as many authors publishing two articles within a specified time period as there are single-publication authors, 1/9 as many publishing three articles, 1/16 as many publishing four articles, etc.
And if 100 authors wrote exactly one article each over a specific period in the discipline, then:
| Portion of articles written | Number of authors writing that number of articles |
|---|---|
| 10 | 100/102 = 1 |
| 9 | 100/92 ≈ 1 (1.23) |
| 8 | 100/82 ≈ 2 (1.56) |
| 7 | 100/72 ≈ 2 (2.04) |
| 6 | 100/62 ≈ 3 (2.77) |
| 5 | 100/52 = 4 |
| 4 | 100/42 ≈ 6 (6.25) |
| 3 | 100/32 ≈ 11 (11.111...) |
| 2 | 100/22 = 25 |
| 1 | 100 |
That would be a total of 294 articles and 155 writers, with an average of 1.9 articles for each writer.
Software
- Friedman, A. 2015. "The Power of Lotka’s Law Through the Eyes of R" The Romanian Statistical Review. Published by National Institute of Statistics. ISSN 1018-046X
- B Rousseau and R Rousseau (2000). "LOTKA: A program to fit a power law distribution to observed frequency data". Cybermetrics 4. ISSN 1137-5019. - Software to fit a Lotka power law distribution to observed frequency data.
See also
- Price's law
References
- ↑ Lotka, Alfred J. (1926). "The frequency distribution of scientific productivity". Journal of the Washington Academy of Sciences 16 (12): 317–324.
Further reading
- Kee H. Chung and Raymond A. K. Cox (March 1990). "Patterns of Productivity in the Finance Literature: A Study of the Bibliometric Distributions". Journal of Finance 45 (1): 301–309. doi:10.2307/2328824. — Chung and Cox analyze a bibliometric regularity in finance literature, relating Lotka's law to the maxim that "the rich get richer and the poor get poorer", and equating it to the maxim that "success breeds success".
External links
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