The document discusses the h-index, a metric created by Jorge Hirsch to measure both the productivity and impact of a researcher's publications. The h-index is defined as the number of papers with at least h citations. This index improves upon metrics like total citations or publications by considering both quantity and citation impact. While originally created for physics, the h-index is now commonly used across disciplines to evaluate researchers and is also applied to journals and groups. The index has advantages over journal impact factors but also limitations, such as not accounting for variations between fields.

1. H-Index

2. Why isn’t impact factor good enough?
Which paper would you consider more significant – a top-tier paper
that has been cited 15 times, or a mid-tier paper that’s been cited
500 times?
Unfortunately, granting agencies or tenure committees that base
their decisions on the journal impact factors support the former.
It’s this frustration that has led many to argue that the evolution of
scientific impact will move away from this metric over the coming
decade.

3. Why isn’t impact factor good enough?
Journals have long been ranked in order of relative “importance” by
their journal impact factor, but that system has come under
increasing fire.
The importance placed on the journal impact factor, calculated by the
average number of citations per article in the previous two years, has
led to many journals gaming the system.
For example, editors are aware that certain types of articles, such as
reviews or techniques, are highly cited and thus will contribute
significantly to the journal impact factor.

4. H-Index (Jorge Hirsch index)
The H-Index is a numerical indicator of how productive and
influential a researcher is.
Or The h-index is an author-level metric that attempts to measure
both the productivity and citation impact of the publications of a
scientist or scholar.
It was invented by Jorge Hirsch in 2005, a physicist at the University
of California.
Originally, Professor Hirsch wanted to create a numerical indication
of the contribution a researcher has made to the field.

5. The influence of the H-index
While the H-index might have been created for the purpose of
evaluating researchers in the area of theoretical physics, its influence
has spread much further.
The index is routinely used by researchers in a wide range of
disciplines to evaluate both themselves and others within their field.
The index is based on the set of the scientist's most cited papers and
the number of citations that they have received in other publications.
The index can also be applied to the productivity and impact of a
scholarly journal as well as a group of scientists, such as a
department or university or country.

6. The influence of the H-index
The definition of the index is that a scholar with an index of h has
published h papers each of which has been cited in other papers at
least h times.
Thus, the h-index reflects both the number of publications and the
number of citations per publication.
The index is designed to improve upon simpler measures such as the
total number of citations or publications.
The index works properly only for comparing scientists working in
the same field.

7. How do I calculate my h-index?
Formally, if f is the function that corresponds to the number of
citations for each publication, we compute the h index as follows.
First we order the values of f from the largest to the lowest value.
Then, we look for the last position in which f is greater than or equal
to the 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 citations, respectively, the h index is
equal to 4 because the 4th publication has 4 citations and the 5th has
only 3.
In contrast, if the same publications have 25, 8, 5, 3, and 3, then the
index is 3 because the fourth paper has only 3 citations.
f(A)=10, f(B)=8, f(C)=5, f(D)=4, f(E)=3 → h-index=4
f(A)=25, f(B)=8, f(C)=5, f(D)=3, f(E)=3 → h-index=3

8. Why is the H-index an improvement?
The index has several advantages over other metrics:
 It relies on citations to your papers, not the journals, which is a truer
measure of quality
 It is not dramatically skewed by a single well-cited, influential paper
(unlike total number of citations would be)
 It is not increased by a large number of poorly cited papers (unlike
total number of papers would be)
 It minimizes the politics of publication. A high-impact paper counts
regardless of whether your competitor kept it from being published
in the top-tier journals…
 It’s good for comparing scientists within a field at similar stages in
their careers
 It may be used to compare not just individuals, but also departments,
programs or any other group of scientists.

9. What are the weaknesses of the h-index?
Critics of the metric suggest it is limited in the following ways:
It counts a highly-cited paper regardless of why it’s being referenced-
eg, for negative reasons
It doesn’t account for variations in average number of publications
and citations in various fields (some traditionally publish and cite
less than others)
It ignores the number and position of authors on a paper
It limits authors by the total number of publications, so shorter
careers are at a disadvantage

10. What are the weaknesses of the h-index?
Critics of the metric suggest it is limited in the following ways:
It has relatively low resolution in that many scientists end up in the
same range since it gets increasingly difficult to increase the h-index
the higher it gets (an h-index of 100 corresponds to a minimum of
10,000 citations)
It, like all metrics, is based on data from the past and may not be a
valid predictor of future performance. However, in a follow-up
publication Jorge Hirsch demonstrated that the h-index is better
than other indicators (total papers, total citations, citations per
paper) at predicting future scientific achievement.