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Citations may contain personal author and/or collective (group or corporate) author names (see summary below). As illustrated by the following graph, the number of personal authors per citation has risen steadily since 1950. There is a small pattern of growth in the number of collective authors in recent years.
Statistics were produced at the conclusion of the NLM 2007 production year and generated from the MEDLINE/PubMed baseline files which consist of all completed records in PubMed. The baseline files exclude PubMed records identified as "in process" or "as supplied by publisher" (approx. 3% of the total). Note that very few citations from 1966-2000 contain collective author data (see #8, below).
The above data is extracted from author_counts.xls (Microsoft Excel file, 63 KB). This Excel workbook includes two spreadsheets with author data by year. Data include counts and averages of personal author names, collective author names, and combined, with the maximum instances of each for every year presented. This data is also available in author_counts_recent.pdf (6 KB) and author_counts.pdf (34 KB, Adobe Acrobat Reader required).
Personal Author Counts
Publication Dates | Total Number Records | Records with Personal Author Information | Author Occurrences | Average # Author Occurrence | Maximum # Author Occurrence |
---|---|---|---|---|---|
All | 16,880,015 |
16,508,270 |
53,117,050 |
3.22 | 743 |
2005-2007 | 1,703,390 |
1,680,328 |
7,617,377 |
4.53 | 650 |
2000-2004 | 2,723,522 |
2,677,253 |
11,087,150 |
4.14 | 743 |
1995-1999 | 2,188,076 |
2,142,972 |
8,095,467 |
3.78 | 230 |
1990-1994 | 1,979,582 |
1,938,074 | 6,593,958 |
3.40 | 30 |
1985-1989 | 1,746,305 |
1,705,746 |
5,355,883 |
3.14 | 77 |
1980-1984 | 1,440,009 |
1,406,260 |
3,985,903 |
2.83 | 50 |
1975-1979 | 1,289,570 |
1,252,133 |
3,124,652 |
2.49 | 49 |
pre-1975 | 3,809,506 |
3,705,449 |
7,256,316 |
1.96 | 26 |
Collective Name (Group or Corporate Author) Counts
Publication Dates | Total Number Records | Records with Collective Name Information | Collective Name Occurrences | Average # Collective Name Occurrence | Maximum # Collective Name Occurrence |
---|---|---|---|---|---|
All | 16,880,015 |
57,436 |
62,225 |
1.08 | 25 |
2005-2007 | 1,703,390 |
21,090 |
23,526 |
1.12 | 25 |
2000-2004 | 2,723,522 | 26,936 |
29,137 |
1.08 | 25 |
1995-1999 | 2,188,076 | 1,634 |
1,664 |
1.02 | 4 |
1990-1994 | 1,979,582 | 1,891 |
1,911 |
1.01 | 4 |
1985-1989 | 1,746,305 | 3,172 |
3,226 |
1.02 | 4 |
1980-1984 | 1,440,009 | 1,676 |
1,721 |
1.03 | 3 |
1975-1979 | 1,289,570 | 856 | 859 | 1.00 | 2 |
pre-1975 | 3,809,506 | 181 |
181 |
1.00 | 1 |
Summary:
Number of Citations: | 16,880,015 |
Number of Citations with Personal Author: | 16,508,270 |
Number of Citations with Collective Name: | 57,436 |
Number of Citations with Personal Author and/or Collective Name: | 16,526,147 |
Number of Citations with no Personal Author: | 371,745 |
Number of Citations with no Collective Name: | 16,822,579 |
Number of Citations with Personal Author(s), no Collective Name: | 16,468,711 |
Number of Citations with Collective Name(s), no Personal Author: | 17,877 |
Number of Personal Authors: | 53,117,050 |
Largest Personal Authors Count (PMID 11289970): | 743 |
Number of Collective Names: | 62,225 |
Largest Collective Names Count (PMID 15617175): | 25 |
Number of Personal Author and/or Collective Name: | 53,179,275 |
Largest Combined Personal Author/Collective Name Count (PMID 11289970): | 744 |
The data in the charts and summary above were extracted from the 2008 Statistical Reports on MEDLINE/PubMed Baseline Data, which include detailed statistics on number of occurrences and byte size of all data elements in the baseline database.
Please note that the policy related to author names in MEDLINE has changed over time:
Current practices and policies on how authorship is reflected in MEDLINE are described in the Fact Sheet: Authorship in MEDLINE. See also more information about the MEDLINE author and corporate author fields.
Last reviewed: 23 May 2008
Last updated: 23 May 2008
First published: 02 July 2002
Metadata| Permanence level: Permanence Not Guaranteed