www.le.ac.uk/library Journal impact factors: use and misuse Ian Rowlands University Library Research Festival 2014 Research Bytes 3
May 16, 2015
www.le.ac.uk/library
Journal impact factors: use and misuseIan RowlandsUniversity LibraryResearch Festival 2014 Research Bytes 3
Journal impact factors
What are journal impact factors?
Where can I find them?
Three common pitfalls
What are journal impact factors?
The journal impact factor 2012 example
papers published in 2010
papers published in 2011
+
The journal impact factor 2012 example
citations accruedduring 2012
papers published in 2010
papers published in 2011
+
÷
The journal impact factor 2012 example
100 citations accrued
during 2012
30 papers published
in 2010
20 papers published
in 2011
+
÷
JIF = 100 citations / 50 papers = 2.0
Where can I find them?
Where can I find them?
Journal Citation Reports
Journal Citation Reports ® Thomson Reuters 2012Immunology subject category
Three common pitfalls
1. Don’t compare IFs across disciplines
Don’t compare IFs across disciplines
History
Economics
Polymer science
Genetics and heredity
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0
Mean journal impact factor (2012)
Source: Thomson Reuters Journal Citation Reports
Don’t compare IFs across disciplines
1 2 3 4 5 6 7 8 9 10 11 12 13
Genetics Mathematics
Years after publication
Cita
tions
reci
eved
Don’t compare IFs across disciplines
1 2 3 4 5 6 7 8 9 10 11 12 13
Genetics Mathematics
Years after publication
Cita
tions
reci
eved
Three common pitfalls
2. Take the rankings with a pinch of salt
Take the rankings with a pinch of salt
0 100 200 300 400 500 600 700 800 900 1000-125%
-100%
-75%
-50%
-25%
0%
25%
50%
75%
100%
125%
150%
175%
Journal size (2011 articles)
Mea
n %
cha
nge
in IF
(201
1 on
201
0)
Take the rankings with a pinch of salt
Three common pitfalls
3. Don’t judge an article by its cover
Don’t judge an article by its cover
Don’t judge an article by its cover
top 10% of articles generate 40% of all citations …
Don’t judge an article by its cover
top 10% of articles generate 40% of all citations …
… 82% of articles are `below average’
Don’t judge an article by its cover
top 10% of articles generate 40% of all citations …
… 82% of articles are `below average’
Bill Gates gets on the train …
Don’t judge an article by its cover
2008 2009 2010 2011 2012
2.051
49.92654.333
2.076 2.244
Acta Crystallographica Section AJournal impact factor
Summary
• DO use IFs to target influential journals for reading or potential publication
• DON’T compare IFs across disciplines
• DON’T take the rankings too literally
• DON’T confuse journal and article level metrics
• DO apply common sense
www.le.ac.uk/library
TOMORROW Don’t lose credit for your researchIan RowlandsUniversity LibraryResearch Festival 2014 Research Bytes 4Attenborough ATT212, 13:00-13:30