Baselines are annualized expected citation rates for papers in a research field.
A citation rate is the average number of citations received by a group of papers published in one research field in a given year. It's calculated by dividing the total number of citations received by all papers in the group (defined by research field and publication year) by the total number of papers in the group. The citation rate for all years is the total number of citations received by all papers in all fields published during the 10-year period divided by the total number of papers.
The time period for citation counts is 10 years, plus partial year counts for the current year (data is updated six times a year). Any paper published in the 10-year period may be cited by any other paper published during the same period.
The citation rate in any single year can serve as a baseline to assess the impact of a paper in the same research field published in that year. Another baseline measure is the all-years citation rate, which is the citation rate for a 10-year period. It is important to recognize that citation counts grow over time. Typically, the citation rate of papers published in the last three years are below the citation rate for all years.
Citation frequency is highly skewed with many infrequently cited papers and relatively few highly cited papers. Consequently, citation rates should not be interpreted as representing the central tendency of the distribution.
Keep in mind that citation rates are calculated from citation counts of papers that meet the criteria for inclusion in ESI. It is reasonable to expect that these rates are higher than those for all papers in a field, but the margin of difference is impossible to determine.
The following excerpt from a Citation Rates Average citation rates are calculated for each year of the 10-year period, based on accumulated citations from the year of publication to the most current bimonthly update. Averages are calculated by adding the citation counts of individual papers and dividing by the number of papers. An average for the full 10-year period is also given in All Years. table reveals that on average, a paper from a Geosciences research field published in 2008 received 9.55 citations, and a paper from an Immunology research field published in 2008 received 20.42 citations. Those citations are from articles published between 2008 and the present. The report does not reveal how many citations are from any single year between 2008 and the present. The 10-year average for Geosciences papers is 9.54, and for Immunology papers it is 20.38. The 10-year averages are calculated from citations from articles published during the same 10-year period.
A percentile defines a fraction or subset of papers in a research field that received a minimum number of citations. The smaller the percentile, the higher the minimum number of citations. Percentile values are baselines for evaluating research impact. For example, if the value of the 1.00% percentile is 15, a paper in the same research field in the same year must receive at least 15 citations to belong to that percentile.
The following sample from a Percentiles The term ”percentile” designates a citation threshold at or above that at which a fixed fraction of the papers fall. This term is used to denote any fixed fraction of top papers ordered by citation count. The levels we have selected for listing by field and year are 0.01%, 0.1%, 1.0%, 10%, 20%, and 50%. table reveals that papers from 2011 that received at least 14 citations fall in the 10% percentile of papers in Microbiology. It follows that 90% of Microbiology papers published in 2011 received fewer than 14 citations.
For all years, Microbiology papers in the 10% percentile received a minimum of 38 citations.
The Field Rankings Field Rankings displays total papers, total citations received, citations per paper, and Hot and Highly Cited papers in each field. table displays aggregate data for each of the 22 ESI research fields. For each field:
- The Number of Papers is the total number of papers in 10 years of Web of Science.
- The Number of Citations is the total number of citations received by all papers in the research field. The citing papers can be in any field.
- Citations per Paper is the total number of citations divided by the total number of papers.
- Highly Cited Papers is the number papers receiving the minimum number of citations to place them in the top 1% of all papers in the field. It is important to recognize that minimum number may be equivalent to the value given in the Citations Per Paper column. It may be smaller or larger.
The following excerpt from a Field Rankings table reveals that in the field of Engineering:
- There are records of 919,038 papers from Engineering journals in 10 years of Web of Science.
- The 919,038 papers received a total of 4,667,747 citations.
- Citations per paper is the quotient obtained by dividing Number of Citations by Number of Papers.
- 8,835 of these papers received a number of citations that placed them in the top 1% of all Engineering papers in the past 10 years.
|Field||Number of Papers||Number of Citations||Citations Per Paper||Highly Cited Papers|