For any set of papers, an Average Percentile can be calculated as the mean of all the percentiles of all the papers in the set. In
the case that a paper is assigned to more than one category, the category in which the percentile value is closest to zero is used (i.e. the best performing value).
The Average Percentile can apply to any set of papers, such as an author’s body of work, all the publications in a journal or the
accumulated publications of an institution, country or region.
The average percentile will represent the average performance of the papers in the set having been normalized for field, year and
document type. The main advantage of the Average Percentile indicator is that it can be used to compare to peer entities regardless of size, age or subject focus. In this regard, it is quite similar to and is a complement to, the Category Normalized Citation Impact indicator.
An advantage of the Average Percentile indicator is that it describes the relative position of a paper compared to similar papers. One
disadvantage is that it does not necessarily indicate the actual number of citations. In the example in Table 6, it can be seen that the
most highly cited paper has 20 times more citations than the second most cited paper, however the percentile of the first paper has a
relatively similar value to the paper in second position. Table 6 is purely for demonstration purposes with a small number of papers.
In a more typical distribution, which may contain thousands of papers, these two papers may have very similar percentiles. This
artifact of the methodology is advantageous as it overcomes the skewed nature of citation based indicators, but at the same time it
is disadvantageous as it may not fully recognize the value of highly cited papers. As with other indicators, it is recommended that the
percentile is used alongside and to complement other indicators.
Complementary indicators that can be used alongside the Average Percentile include:
Percentile in Subject Area
The Category Normalized Citation Impact (CNCI) of a document is calculated by dividing the actual
count of citing items by the expected citation rate for documents with the same document type, year of
publication and subject area. When a document is assigned to more than one subject area, an average
of the ratios of the actual to expected citations is used. The CNCI of a set of documents, for example,
the collected works of an individual, institution or country, is the average of the CNCI values for all the
documents in the set.
For a single paper that is only assigned to one subject area, this can be represented as:
For a single paper that is assigned to multiple subjects, the CNCI can be represented as the average of the
ratios for of actual to expected citations for each subject area:
For a group of papers, the CNCI value is the average of the values for each of the papers, represented as:
Where: e = the expected citation rate or baseline, c = Times Cited, p = the number of papers, f = the field
or subject area, t = year, d = document type, n = the number of subjects a paper is assigned to and i = the entity being evaluated (institution, country, person, etc).
CNCI is a valuable and unbiased indicator of impact irrespective of age, subject focus or document type. Therefore, it allows comparisons between entities of different sizes and different subject mixes. A CNCI value of one represents performance at par with world average, values above one are considered above average and values below one are considered below average. A CNCI value of two is consideredtwice world average.
Note:A quirk of the way baselines are calculated (whole counting of subjects for papers in more than one subject category) and the way CNCI is calculated (fractional counting of subjects for papers in more than one subject category) results in the CNCI of the world not being equal to one exactly.
CNCI is an ideal indicator for benchmarking at all organizational levels (author, institution, region etc). One can also use CNCI to identify impactful sub-sets of documents and assess any research activity. For example, an institution may use the CNCI to assess which collaborations are the most impactful or identify new potential collaboration opportunities. Or to identify the performance of up-and-coming researchers compared to established ones and to aid with faculty recruitment by assessing candidates. As a funding organization, one may use the CNCI as a quantitative performance indicator to monitor the performance of funded projects, or assess the track record of a research teams applying for a new funding.
There are known issues with using CNCI:
To overcome these issues there are some steps that can be taken:
Complementary indicators that can be used alongside the CNCI include:
The Citation Impact of a set of documents is calculated by dividing the total number of citations by the total number of publications.
Citation Impact shows the average number of citations that a document has received
Citation Impact has been extensively used as a bibliometric indicator in research performance evaluation and can be applied at all
organizational levels (author, institution, country/region, research field or journal). However, there are limitations to the indicator. For
example, it ignores the total volume of research outputs.
Example of Citation Impact at the Author Level:
|Total Publications||Total Citations||Citation Impact|
Researcher A has only one publication that has received 50 citations while Researcher B has published 10 documents that have
received 200 citations. Researcher A has a higher Citation Impact (50) than Researcher B (20), even though Researcher B has published more documents and received more citations overall.
At the field level, the Citation Impact of certain disciplines is often higher than in other scientific fields due to several factors, such as the degree to which references from other fields are cited.
InCites facilitates several views of collaborations (co-authored publications) within its interface that enable the user to identify and
evaluate collaborations at various levels (country/region, institution, person). Any of the indicators described in this Handbook are
available as subsets of any document set. For example, it is very simple to create an analysis to evaluate the performance of any
collaboration. Furthermore, once the collaboration has been identified, it is straightforward to drill down to identify the individual
people, subjects or papers that make up the collaboration.
The ESI Most Cited indicator is only for organizations, and shows whether an institution is ranked within the top one percent worldwide,
in terms of numbers of citations, based on 10 years of publications. The ESI Most Cited indicator is calculated at the institutional level
and is normalized for each of the 22 ESI research areas. ESI Most Cited institutions have to be within the top one percent in at least one
of the 22 ESI research areas.
The h-index (also known as Hirsch index) was introduced by J. Hirsch in 2005 and can be defined as follows: A researcher has an
h-index, if he/she has at least h publications for which he/she has received at least h citations. For example, Researcher A has an
h-index = 13 if he/she has published at least 13 documents for which he/she has received at least 13 citations each. Its popularity as a bibliometric indicator has derived from the fact that it combines productivity (number of documents) and impact (number of citations) in one index.
The h-index can be applied to any level of aggregation (author, institution, journal, etc.) and it can reveal information about how
the citations are distributed over a set of documents. At the author level, it is considered to be an indicator of a researcher’s lifetime
scientific achievements. Some clear advantages of the h-index are that it is a mathematically simple index, it encourages large
amounts of impactful research work while at the same time discourages publishing unimportant output and that single highly cited
publications do not influence the h-index (unlike the Citation Impact).
However, the h-index is a time-dependent measure, as it is proportional to the length of a researcher’s career and how many articles
they have published. For example, early career researchers would be at a disadvantage when compared to more senior researchers
because the latter would have had more time to produce more work and receive more citations for their output.
|Total Publications||Total Citations||Citation Impact||h-Index|
Researcher A has only one publication that has received 50 citations, while Researcher B has published 10 documents that have received 20 citations each. Researcher C has the same number of publications and citations as Researcher B. According to the definition of the h-index, Researcher A, who has only one publication and has received 50 citations will have an h-index = 1, whereas Researcher B who has 10 publications and has received 20 citations for each publication will have an h-index = 10. Researcher C has an h-index = 5, which means that even though he/she has published the same number of documents and received the same number of citations as Research B, Researcher’s C citations are more concentrated in five documents that are more cited than the rest of his/her publications.
Note, however, that in this example we have not taken into account the researchers’ ages (the time interval between when the first and last document were published) and the disciplines that the researchers are active in. The h-index can be very different across disciplines due to the differences in the average citation rates and therefore, sensitive to the disciplinary background of research output, as research entities publish in different subject mixes.
Assessing the productivity of a large set of publications is the first step in a series of bibliometric analyses that we can apply in order to obtain a deeper understanding of the performance of our research output.
The Highly Cited Papers indicator shows the volume of papers that are classified as highly cited in the Clarivate Analytics service known as Essential Science Indicators (ESI). ESI is a separate service also hosted on the InCites platform and should not be confused with the subject schema of the same name.
Highly Cited Papers in ESI are the top one percent in each of the 22 subject areas represented in the Web of Science, per year. They are based on the most recent 10 years of publications. Highly Cited Papers are considered to be indicators of scientific excellence and top performance and can be used to benchmark research performance against field baselines worldwide.
Although Highly Cited Papers are synonymous with % Documents in the Top 1% in InCites, they are not the identical because of differences in subject schema, time period and document type.
% Highly Cited Papers
Impact Relative to World indicator is the ratio of the Citation Impact of a set of documents divided by
the world Citation Impact for a given period of time. This indicator can be applied at the institutional,
national and international level. It shows the impact of the research in relation to the impact of the global
research and is an indicator of relative research performance. The world average is always equal to one. If
the numerical value of the Impact Relative to World exceeds one, then the assessed entity is performing
above the world average. If it is less than one, then it is performing below the world average.
Note that although this indicator does normalize for year, it does not take into account the differences in
the subject mix that an institution or a country is publishing in; therefore it is recommended to use it in
conjunction with bibliometric indicators that do take into account the differences in the average citation
rates of the set of documents under evaluation.
Institutional Profiles provide quantitative data for a large number of performance indicators, including:
• Number of staff and students
• Teaching and research reputation
Graphs, accompanied by tabular data, enable you to track the performance of institutions over time and to compare institutions on the basis of a wide range of performance measures.
The following Institution Profiles indicators are available in InCites (see Help file for definitions):
International collaborations are considered to be a way to develop and disseminate scientific knowledge and a driver of scientific impact (number of citations). Internationally co-authored documents gain more visibility in the global scientific community and tend to receive more citations.
The International Collaborations indicator shows the number of publications that have been found with at least two different countries
among the affiliations of the co-authors. The International Collaborations indicator can be applied to any level of aggregation (author,
institution, national, journal or field).
The definition of an internationally collaborative document is a relatively simple indicator that only takes into account if a document is
international (two or more countries) or not. It does not take into account the total number of countries represented in the publication.
% of International Collaborations
The Journal Normalized Citation Impact (JNCI) indicator is a similar indicator to the Category Normalized Citation Impact, but instead of normalizing per subject area or field, it normalizes the citation rate for the journal in which the document is publishing.
The Journal Normalized Citation Impact of a single publication is the ratio of the actual number of citing items to the average citation
rate of publications in the same journal in the same year and with the same document type. The JNCI for a set of publications is the
average of the JNCI for each publication.
The JNCI indicator can reveal information about the performance of a publication (or a set of publications) in relation to how other
researchers perform when they publish their work in a given journal (or a set of journals). It can provide the answers to questions, such as “How do my papers perform in the journals I publish?” If the numerical value of the JNCI exceeds one, then the assessed research entity is performing above average. If it is less than one, then it is performing below the average.
The JNCI indicator is also useful for publishers as a measure of post–publication performance and it can reveal which research work
exceeds average performance and therefore increases the citation rates of a journal.
|Total Publications||Total Citations||Citation Impact||h-Index||CNCI||JNCI|
Researcher D and Researcher E both have very similar numbers of publications and citations. Their Citation Impact is almost the same, and their h-index is identical. Using only the first four indicators featured in table 4 (above), it is not possible to distinguish the performance of the two researchers. However, the two researchers may in fact be conducting research in very different fields and may have a different history of publication (older papers vs new papers). Using the CNCI and JNCI indicators gives us a better understanding of their performance relative to their peers in terms of subject, document type and age of publication.
From the normalized indicators, one can quickly identify that Researcher D has both CNCI (1.32) and JNCI (1.86) values that are above average (>1). While Researcher E has a CNCI (0.45) and JNCI (0.72) that are below average (<1).
It should be noted that the JNCI is a relative research performance indicator. Even though in many cases CNCI and JNCI might correlate positively, this might not always be the case. For example, if for a given researcher the CNCI indicator is above average while at the same time the JNCI indicator is below average, this might mean that the researcher receives more citations than the average for his/her published research work in the scientific field that the researcher is active in overall, but he/she publishes in journals that have very high citation rates (e.g. Nature or Science) and has received less citations than the average published work does for the given journals.
The percentile of a publication is determined by creating a citation frequency distribution for all the publications in the same year,
subject category and of the same document type (arranging the papers in descending order of citation count), and determining the
percentage of papers at each level of citation, i.e., the percentage of papers cited more often than the paper of interest. If a paper has a percentile of value of one, then 99 percent of the papers in the same subject category, year and of the same document type have a citation count that is lower.
A percentile indicates how a paper has performed relative to others in its field, year and document type and is therefore a normalized
The %Documents Cited indicator is the percentage of publications, in a set, that have received at least one citation. It shows the extent
to which other researchers in the scientific community utilize the research output produced by an entity. Another way of thinking about
this indicator is as the inverse of the number of papers that didn’t get cited at all.
Note that the %Documents Cited indicator will vary depending on the selected time period and publication types included in the
analysis. The % Documents Cited is not a normalized indicator. For example, if the analysis includes documents that have been
published during the current or recent years, some of these documents may not have had time to accrue citations.
Complementary indicators include:
The % Documents in Top 1% indicator is the top one percent most cited documents (as defined in the description of Average Percentile) in a given subject category, year and publication type divided by the total number of documents in a given set of documents, displayed as a percentage. A higher value is considered to be higher performance. A value of “1” for a set of documents represents that one percent of the publications in that set are in the top one percent of the world regardless of subject, year and document type and would therefore be considered to be performing at the same level as world average. A value above “1” represents that more than one percent of papers in the set are in the top one percent of the world and a value of less than “1” would represent that less than one percent of the papers in the set are in the top one percent of the world.
The % Documents in Top 1% indicator is considered to be an indicator of research excellence as only the most highly cited papers would make the top one percent in their respective field, year and document type. The indicator can be used in conjunction with other indicators to provide a more complete picture of performance. The % Documents in Top 1% indicator can be applied to any level of aggregation (author, institution, national/international, field).
Although the top one percent is a relevant measure of excellence, by its nature it is typically only a small percentage of any document set and therefore the statistical relevance of small sample sizes is a significant concern.
The % Documents in Top 1% is best used with large datasets such as the accumulated publications of an institution, country or region and for a publication window of several years. The % Documents in Top 10% is very similar to the % Documents in Top 1% simply with a threshold of 10 percent instead of one percent. Therefore, typical performance will be around a value of 10 and values of higher than 10 would be considered above average performance. The two indicators complement each other very well to give a broader picture of highly performing research (10 percent) and excellence (one percent).
The % Documents in Top 10% is also more appropriate than the % Documents in Top 1% when the size of the data set is smaller.
However, it is still only appropriate for large to medium size data sets and should be used with a great deal of caution when looking at
small datasets such as the output of an individual author.
Complementary indicators include:
The % Highly Cited Papers indicator shows the number of ESI Highly Cited Papers for an entity (paper, author, institution, country,
journal and field) divided by the total number of documents produced by the given entity, represented as a percentage.
It is a measure of excellence and can show what percentage of an institutions output is among the most impactful papers in the world.
Highly Cited Papers
As with Highly Cited Papers, a Hot Paper is a designation of a paper within ESI.
The Hot Papers indicator shows the number of papers in the top 0.1 percent worldwide that were published in the last two years, based on citation activity in the most recent two month period, per ESI subject field. Hot Papers are indicators of emerging scientific impact as they reveal which recent papers are currently attracting the attention of the global research community.
The % Hot Papers indicator shows the number of Hot Papers for an entity (author, institution, country and journal) divided by the total
number of documents produced by the given research entity times 100.
An industry collaborative publication is one that lists its organization type as “corporate” for one or more of the co-author’s affiliations.
The % of Industry Collaborations is the number of industry collaborative publications for an entity (as described above) divided by the
total number of documents for the same entity represented as a percentage.
Note: It is not possible to unify the data for every single affiliation of all the publications in InCites, therefore only those entities that
have been unified will have an organization type. There will be corporate affiliations that have not yet been unified, will not have an
organization type and therefore will not be identified as an industrial collaboration. Clarivate Analytics has made considerable efforts
to identify the largest corporations and unify them, however this tends to focus on large multinational corporations and may lead to
regional bias. In the future, as more organizations are unified, the number of industry collaborative papers is expected to increase.
The % of International Collaborations is the number of International Collaborations for an entity divided by the total number of documents for the same entity represented as a percentage.
The % of International Collaborations is an indication of an institution or author’s ability to attract international collaborations.
See the complete list of indicators definitions in the online help file for InCites Benchmarking & Analytics