h -index is a writer-level metric that attempts to measure the impact of productivity and publicity quotes from scientists or scholars. This index is based on a collection of the most cited papers of scientists and the number of citations they have received in other publications. This index can also be applied to the productivity and impact of scientific journals as well as a group of scientists, such as a department or university or country. The index was proposed in 2005 by Jorge E. Hirsch, a physicist at UCSD, as a tool for determining the relative quality of theoretical physicists and is sometimes called the Hirsch Hirsch index or Hirsch's number .
Video H-index
Definition and destination
The index definition is that a scholar with index h has published h papers each of which has been quoted in another paper at least h times. Thus, h -index reflects both the number of publications and the number of citations per publication. This index is designed to improve the simpler size such as the total number of citations or publications. The index works well only to compare scientists working in the same field; Citation conventions differ widely among the various fields.
Maps H-index
Calculation
Formally, if f is a function corresponding to the number of citations for each publication, we compute the index h as follows. First we order the value f from the largest value to the lowest value. Then, we look for the last position where f is greater than or equal to position (we call h this position). For example, if we have a researcher with 5 publications A, B, C, D, and E with 10, 8, 5, 4, and 3 quotes, respectively, the index h equals 4 because the 4th publication has 4 citations and the fifth is only 3. Conversely, if the same publication has 25, 8, 5, 3, and 3, then the index is 3 because the fourth paper has only 3 citations.
Jika kita memiliki fungsi f yang dipesan dalam urutan menurun dari nilai terbesar ke yang terendah, kita dapat menghitung indeks h sebagai berikut:
- h -index (f) =
The Hirsch index is equivalent to the Eddington number, the previous metric used to evaluate cyclists. The h -index serves as an alternative to more traditional journal impact factor metrics in evaluating the impact of a particular researcher's work. Since only the most cited articles contribute to h -index, the determination is a simpler process. Hirsch has shown that h has a high predictive value for whether a scientist has won an award such as a National Academy or Nobel Prize membership. The h -index grows as a citation accumulates and thus it depends on the "academic age" of a researcher.
Input data
h -index can be manually specified using citation data or using automated tools. Subscription-based databases such as Scopus and Web of Science provide automated calculators. Harzing's Publish or Perish program calculates h -index based on Google Scholar entries. Starting July 2011, Google has provided the index and i10-hexadecimal indexes h calculated automatically in their own Google Scholar profile. In addition, specific databases, such as the INSPIRE-HEP database can automatically calculate h -index for researchers working in high-energy physics.
Each database tends to produce different h for the same undergraduate, because of different scopes. A detailed study shows that the Web of Science has a strong journal publishing coverage, but poor coverage of high-impact conferences. Scopus had better conference coverage, but poor publishing coverage before 1996; Google Scholar has the largest scope of conferences and journals (though not all), but as Scopus has limited scope for publications prior to 1990. The exclusion of conference conference papers is a special issue for scholars in computer science, where the conference process is considered an essential part of the literature. Google Scholar has been criticized for producing "ghost excerpts," including gray literature in the number of citations, and failing to follow Boolean logic rules when combining search terms. For example, Meho and Yang's research found that Google Scholar identifies 53% more citations than Web of Science and Scopus combined, but notes that because most of the additional quotes reported by Google Scholar come from low-impact journals or conference processes, they do not significantly change the relative ranking of individuals. It has been suggested that to handle the sometimes wide variation in h for a single academic measured across the database of possible citations, one must assume false negatives in a database is more problematic than a positive error and take maximum h is measured for an academician.
Compare results across career fields and levels
Small systematic investigations have been conducted on how h -index behaves over various institutions, countries, times and academic fields/disciplines, but it is clear that the differences between disciplines can be a factor x10 and more. Also, h values ​​have increased in recent decades. Academics with h 20 can be simple scientists, or leaders in their fields.
Comparing results between individuals should take into account (a) the career stage, (b) the frequency of publications in the field, and (c) the frequency of citations in the field. An individual (a) at a more senior career stage will publish more and publications will have more time to collect citations. How many publications a writer or coauthor per year (b), and many excerpts that attract publications per year (c) differ greatly between academic fields. How many more senior persons (a) are quoted differently from one field to another - ie. in general lab science to always quote the lab director. How quotes are distributed from time to time (c) are different - eg. the publication of medical science attracted many quotations in the first years, while the publication of the humanities has a slower but more durable citation pattern. Finally, the correlation between publication and "success" varies widely between fields and other social factors (eg, Oxford/Cambridge don used to care about peer recognition, but not publicity or citation).
Hirsch suggests that, for physicists, the value for h is about 12 may be typical for an advancement to tenure (associate professor) at a large research university [AS]. A value of about 18 could mean a full professorship, 15-20 could mean a fellowship in the American Physical Society, and 45 or higher could mean membership at the National Academy of Sciences of the United States.
For most cited scientists in the 1983-2002 period, Hirsch identified the top 10 in the life sciences (in order to lower
Among the 22 disciplines listed in Thomson Reuters Essential Science Indicators Citation Thresholds [thus excluding non-science academics], physics has the second most quote after space science. During the period January 1, 2000 - February 28, 2010, a physicist must receive 2073 citations to become one of the most cited 1% of physicists in the world. The threshold for space science is the highest (2236 citations), and physics is followed by clinical medicine (1390) and molecular biology & amp; genetics (1229). Most disciplines, such as environment/ecology (390), have fewer scientists, fewer papers, and fewer quotations. Therefore, this discipline has a lower citation threshold in the Essential Science Indicator, with the lowest quoted threshold observed in social sciences (154), computer science (149), and multidisciplinary science (147).
The numbers are very different in the social disciplines: The Social Science Impact Team at the London School of Economics finds that social scientists in the UK have a lower average h-index. The h-index for professors ("full"), based on Google Scholar data ranges from 2.8 (in law), up to 3.4 (in political science), 3.7 (in sociology), 6.5 (in geography) and 7.6 (in economics). On average across disciplines, a professor in social sciences has a h-index about twice that of a senior lecturer or lecturer, although the difference is the smallest in geography.
Benefits
Hirsch intends h -index to address the major weaknesses of other bibliometric indicators, such as number of papers or total number of citations. The total number of papers does not take into account the quality of scholarly publications, while the total number of citations may be disproportionately affected by participation in a major publication of influence (eg, methodological papers proposing successful techniques, methods or new estimates, which may produce a large number of citations), or has many publications with several quotes each. The h -index is meant to measure simultaneously the quality and quantity of scientific output.
Criticism
There are a number of situations where h can provide misleading information about a scientist's output: Most of these are not exclusive to h -index.
- The h -index does not take into account the number of typical citations in different fields. It has been suggested that citation behavior is generally influenced by field-dependent factors, which can undo comparisons not only across disciplines but even in different fields of research from one discipline.
- The h -index discards the information contained in the author's placement in the author's list, which in some scientific fields is significant.
- The h -index has been found in one study to have less accuracy and prediction accuracy than the simple size of the average quote per paper. However, these findings are disputed by another study by Hirsch.
- The h -index is a natural number that reduces its discriminatory power. Ruane and Tol therefore suggest a rational interpolation between h and h 1.
- h -index can be manipulated through self-citations, and if based on Google Scholar output, then even computer-generated documents can be used for that purpose, for example using SCIgen.
- The h -index does not provide a significantly more accurate impact gauge than the total number of citations for a particular scholar. Specifically, by modeling the distribution of quotes between papers as random integer partitions and h -index as Durfee's square of the partition, Yong arrives at the formula , where N is the total number of citations, which, for members of the National Academy of Sciences mathematics, typically within 10-20 percent) estimates of h -index in most cases.
Alternatives and modifications
Source of the article : Wikipedia
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