The Journal Impact Factor 2020

DOI: 10.3238/dzz-int.2021.0023

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Keywords: EbM Bits JIF Journal Impact Factor

 

Department of Oral Health & Medicine, University Center for Dental Medicine Basel UZB: Jens C. Türp, DDS, Dr med dent, MSc, M.A., Professor

Citation: Türp JC: The Journal Impact Factor 2020. Dtsch Zahnärztl Z Int 2021; 3: 195–199

DOI.org/10.3238/dzz-int.2021.0023

On June 30, 2021, the Clarivate™ media group published the 2020 rankings of scientific journals with impact factor in its Journal Citation Reports. In the year under review, 12,279 of the 20,932 journals considered had a journal impact factor (JIF). The calculation of the JIF is shown in Figure 1. The current JIFs of dental journals are presented below, followed by the scientific journals with the highest JIF. The annual review is complemented by a critical discussion of the JIF.

Included journals and general development

As in the calculation years 2019 and 2020, there are 91 journals with a JIF in the category Dentistry, Oral Surgery & Medicine (Table 1). Included for the first time is the Japanese Dental Science Review; Brazilian Oral Research is no longer listed.

JIF

rank

2020

Journal

JIF

2020

JIF

2019

JIF

rank

2019

1

Journal of Clinical Periodontology

8.728

5.241

2

2

Periodontology 2000

7.589

7.718

1

3

Journal of Periodontology

6.993

3.742

7

4

International Journal of Oral Science

6.344

3.047

12

5

Journal of Dental Research

6.116

4.914

3

6

Clinical Oral Implants Research

5.977

3.723

8

7

Oral Oncology

5.337

3.979

5

8

Dental Materials

5.304

4.495

4

9

Journal of Evidence-Based Dental Practice

5.267

2.426

22

10

International Endodontic Journal

5.264

3.801

6

11

Japanese Dental Science Review

5.093

---

---

12

Journal of Prosthodontic Research

4.642

2.662

17

13

Journal of Periodontal Research

4.419

2.926

13

14

Journal of Dentistry

4.379

3.242

10

15

Journal of Oral Pathology & Medicine

4.253

2.495

20

16

Journal of Endondontics

4.171

3.118

11

17

Caries Research

4.056

2.186

30

18

Clinical Implant Dentistry and Related Research

3.932

3.396

9

19

Journal of Oral Rehabilitation

3.837

2.304

25

20

Journal of the American Dental Association

3.634

2.803

16

21

Clinical Oral Investigations

3.573

2.812

15

22

Molecular Oral Microbiology

3.563

2.905

14

23

Oral Diseases

3.511

2.613

19

24

International Journal of Paediatric Dentistry

3.455

1.993

35

25

Journal of Prosthetic Dentistry

3.426

2.444

21

26

Community Dentistry and Oral Epidemiology

3.383

2.135

31

27

Dental Traumatology

3.333

1.530

57

28

European Journal of Oral Implantology

3.123

2.619

18

29

European Journal of Orthodontics

3.075

2.202

28

30

Gerodontology

2.980

1.339

69

31

Journal of Esthetic and Restorative Dentistry

2.843

1.786

45

32

International Journal of Oral and Maxillofacial Implants

2.804

2.320

24

33

Oral and Maxillofacial Surgery Clinics of North America

2.802

1.554

55

34

International Journal of Oral and Maxillofacial Surgery

2.789

2.068

33

35

BMC Oral Health

2.757

1.911

38

36

Journal of Prosthodontics – Implant, Esthetic, and Reconstructive Dentistry

2.757

2.187

29

37

Progress in Orthodontics

2.750

1.822

42

38

Journal of Applied Oral Science

2.698

1.797

43

39

American Journal of Orthodontics and Dentofacial Orthopedics

2.650

1.960

36

40

Odontology

2.634

1.840

41

41

Archives of Oral Biology

2.633

1.931

37

42

Journal of Periodontal and Implant Science

2.614

1.847

40

43

European Journal of Oral Sciences

2.612

2.220

26

44

Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology

2.589

1.601

51

45

International Dental Journal

2.512

2.038

34

46

International Journal of Dental Hygiene

2.477

1.229

75

47

Implant Dentistry

2.454

1.452

64

48

Operative Dentistry

2.440

2.213

27

49

Dentomaxillofacial Radiology

2.419

1.796

44

50

International Journal of Implant Dentistry

2.384

2.111

32

51

Journal of Adhesive Dentistry

2.359

2.379

23

52

European Journal of Dental Education

2.355

1.050

82

53

Acta Odontologica Scandinavica

2.331

1.573

54

54

Australian Dental Journal

2.291

1.401

66

55

Journal of Dental Education

2.264

1.322

71

56

European Journal of Paediatric Dentistry

2.231

1.500

60

57

Head & Face Medicine

2.151

1.882

39

58

Dental Materials Journal

2.102

1.359

67

59

Journal of Dental Sciences

2.080

1.034

83

60

Angle Orthodontist

2.079

1.549

56

61

Journal of Cranio-Maxillofacial Surgery

2.078

1.766

46

62

Medicina Oral, Patología Oral y Cirugía Bucal

2.047

1.596

52

63

Cranio – The Journal of Craniomandibular Practice

2.020

1.173

78

64

Journal of Orofacial Orthopedics – Fortschritte der Kieferorthopädie

1.938

1.286

73

65

Journal of Advanced Prosthodontics

1.904

1.504

59

66

Journal of Oral and Maxillofacial Surgery

1.895

1.642

49

67

International Journal of Computerized Dentistry

1.883

1.714

48

68

Pediatric Dentistry

1.874

1.594

53

69

Journal of Oral Facial Pain & Headache

1.871

1.260

74

70

Oral Radiology

1.852

0.540

89

71

International Journal of Periodontics & Restorative Dentistry

1.840

1.513

58

72

Orthodontics & Craniofacial Research

1.826

1.455

63

73

Journal of Public Health Dentistry

1.821

1.743

47

74

Journal of Oral Implantology

1.779

1.424

65

75

International Journal of Prosthodontics

1.681

1.490

61

76

Quintessence International

1.677

1.460

62

77

Australian Endodontic Journal

1.659

1.120

80

78

British Journal of Oral & Maxillofacial Surgery

1.651

1.061

81

79

British Dental Journal

1.626

1.306

72

80

Journal of Stomatology, Oral and Maxillofacial Surgery

1.569

1.152

79

81

Journal of Oral Science

1.556

1.200

76

82

American Journal of Dentistry

1.522

0.957

84

83

Cleft Palate-Craniofacial Journal

1.433

1.347

68

84

Korean Journal of Orthodontics

1.372

1.326

70

85

Community Dental Health

1.349

0.679

87

86

Journal of the Canadian Dental Association

1.316

1.200

76

87

Oral Health & Preventive Dentistry

1.256

0.920

85

88

Journal of Clinical Pediatric Dentistry

1.065

0.798

86

89

Seminars in Orthodontics

0.970

0.625

88

90

Australasian Orthodontic Journal

0.226

0.113

91

91

Implantologie

0.125

0.123

90

---

Brazilian Oral Research

---

1.633

50

Table 1 Journal impact factor (JIF) for 2020 for the 91 journals listed in the category Dentistry, Oral Surgery & Medicine with comparison of the previous year‘s JIF (n = 91)

The 2020 JIF values range from 0.125 (the German-language journal Implantologie) to 8.728 (Journal of Clinical Periodontology). The latter value is the highest JIF ever achieved for a dental journal; the peak value of the previous year (7.718, Periodontology 2000) was exceeded by 1.01 points. Only two journals (Peri­odontology 2000; Journal of Adhesive Dentistry) have an (insignificantly) lower JIFs than in the previous year; for all other journals, the JIF has increased.

The first 3 places are shared by periodontology journals – a first in the history of the JIF ranking. Table 2 illustrates the JIF-related rise of the Journal of Clinical Periodontology; the jump of nearly 3.5 JIF points from 2019 to 2020 is remarkable.

Jahr

JIF

2020

8.728

2019

5.241

2018

4.164

2017

4.046

2016

3.477

2015

3.915

2014

4.010

2013

3.610

2012

3.688

2011

2.996

2010

3.933

2009

3.549

2008

3.193

2007

2.678

2006

2.380

2005

2.225

2004

1.644

2003

1.582

2002

1.736

2001

1.641

2000

1.426

1999

1.873

1998

1.679

1997

1.812

Table 2 Development of the JIF of the Journal of Clinical Periodontology between 1997 and 2020.

To compare the JIF of dental journals with those of other scientific disciplines, Table 3 shows the 20 scientific journals with the highest JIF values.

JIF-Rang

2020

Zeitschrift

JIF

2020

1

CA-A Cancer Journal for Clinicians

508.702

2

Nature Reviews Molecular Cell Biology

94.444

3

New England Journal of Medicine

91.245

4

Nature Reviews Drug Discovery

84.694

5

Lancet

79.321

6

Nature Reviews Clinical Oncology

66.675

7

Nature Reviews Materials

66.308

8

Nature Energy

60.858

9

Nature Reviews Cancer

60.716

10

Nature Reviews Microbiology

60.633

11

Chemical Reviews

60.622

12

MMWR Surveillance Summaries

58.769

13

Journal of the American Medical Association

56.272

14

MMWR Recommendations and Reports

55.857

15

Nature Biotechnology

54.908

16

Chemical Society Reviews

54.564

17

Reviews of Modern Physics

54.494

18

Nature Medicine

53.440

19

Nature Reviews Genetics

53.242

20

Nature Reviews Immunology

53.106

12,279

Sen-I Gakkaishi (Journal of the Society of Fiber Science and Technology, Japan)

0.013

Table 3 The 20 scientific journals with the highest journal impact factor (JIF) and the tail end of the ranking of 2020.

“The present analysis disqualifies the JIF from adequately represen­ting the citation frequency of a journal or article.”

Priv.-Doz. Dr. Tobias Kisslich et al., Salzburg [4]

Criticism of the JIF

Reading and publishing behavior has changed fundamentally over the past few decades. Nestor et al. [6] note: “Apart from any personal subscriptions a researcher might have, performing a primary literature search used to involve a visit to the local library, sorting through each journal’s table of contents and indices, finding articles of interest, and making notes and copies for use. If a library didn’t have a local copy of a particular journal, waiting days to weeks after requesting one was the next step. The JIF was quite useful during that era, as a library could best utilize its lim­ited budget to keep a selection of journal subscriptions likely to meet most of the needs of its patrons.”

The authors [6] further state: “With the proliferation of computers and the internet, we now can generate thousands of relevant results in a matter of milliseconds. Filtering by year of publication, keyword, au­thors, and various other options allows for fine-tuned querying. With a few clicks, nearly any article can then be downloaded and saved, although payment for access is often required. The granularity and breadth afforded by the modern literature search have shifted the search me­chanics from journal-oriented to article-oriented, and with that shift, the JIF has di­min­ished in value.”

The prestigious University College London noted in an August 2020 announcement: “In the pre-digital era, the unit of distribution for science was the physical journal volume. Libraries needed to make decisions on which journals to purchase and retain, and so the JIF was developed with no intention of reflecting research quality – but rather research readership and use. A journal with a high impact factor likely had a large number of potential readers, and the journal was likely to be heavily used. [… ] Because the impact factor was for so long the only citation-based metric readily available, it became popular as a metric of quality [… ]. But metrics are now easily attributed directly to the individual articles – we can count how many people are reading, downloading, and citing a journal article. This means that we no longer need to estimate the impact of papers when we can get that data directly, more informatively, and more accurately.” [10].

General Recommendation

There has been no doubt in the literature for years that the JIF developed by Eugene Garfield [3] has outlived its usefulness (Tables 4 and 5). Therefore, the first academic institutions have now drawn conse­quences. The renowned University College London, for instance, has announced that it will no longer use the JIF as an indicator of the quality of an article.

Citation

Source

“Despite recognition of many disadvantages and misuses of JIF, it is still prominently used in journal ranking and calculation of research productivity, leading to inaccuracies in these assessments.”

Mech et al. [5]

“Journal impact factor may have little to no association with study results, or methodological quality.”

Saginur et al. [7]

“The JIF is an extraordinarily poorly used metric, which has led some commentators to suggest it may be the cornerstone of an unhealthy research culture with the potential to distort the scientific process.”

University College London [10]

“The average number of citations per paper in a journal over two years sounds straightforward – except that’s not quite how the JIF is calculated. Averages are usually calculated by dividing the sum of the values for a sample of observations (numerator) by the number of those observations (denominator). Note simple averages are usually symmetrical – which means the sum of the sample is based only on the observations counted in the denominator. But the JIF isn’t calculated in this way. Instead, the numerator – sum of citations – is based on all of the citations received by items in a given journal. This includes articles and reviews, but also letters to the editor, comments, and other front matter that aren’t primary research articles – even news and obituaries; while the denominator is based not on the number of cited documents, but only articles and reviews. Hence, a journal’s impact factor is driven not only by their research articles, but inflated by the other accompanying material in the journal. While this doesn’t always get very heavily cited, it does usually add some extra citations.”

University College London [10]

“The JIF is an unreliable, biased, and inherently flawed method of measuring the quality, accessibility, and value of a research journal. While it has played an important and valuable role in helping scientists find and acquire knowledge over the last six decades, our movement into the digital and cross-specialty age has depreciated the value of the JIF as the manner in which we seek and obtain knowledge has fundamentally changed.”

Nestor et al. [6]

“The JIF should not be used to assess the quality and impact of individual scientific work.”

Asaad et al. [1]

Table 4 Critical statements about the JIF.

 

General statements

The JIF is only a limited accurate predictor of journal quality.

The JIF is not a valid measure of the quality of individual publications and/or authors.

The JIF does not account for the skewed citation distribution that results from individual highly cited articles. Therefore, it cannot make reliable statements about how often a published article will be cited in the future.

The JIF misleads readers to reject “low-impact” journals that have no perceived higher “net quality” compared to “high-impact” journals, but may still contain a number of “high-quality” articles.

Validity and reliability of the JIF for cross-discipline comparison are limited.

Calculation of the JIF

The database used to calculate the JIF (Science Citation Index) does not include citations from journals outside its own database.

The selection of journals to be included in the database is not transparent.

The definition of what counts as “citable” in the JIF calculation is unclear.

Numerator and denominator have different contents.

The JIF can be easily manipulated to inflate the values:

·  Editors or peer reviewers send authors articles to include in citations.

·  ​The denominator is minimized by removing certain publications from the total number of articles published.

·  The “type” of an article is changed to increase the likelihood that it will be excluded from the denominator.

Withdrawn articles are still included in the JIF score.

Misreferenced articles can account for up to one-third of references, reducing the chances of correctly counted citations.

Bias due to language and article type

There is a preference for English-language journals published in the United States and the United Kingdom.

Articles published in English or by an author with a conventional English name increase the likelihood of being cited.

There is a preference for review articles.

The JIF encourages self-citation (self-reference) without correcting such a strategy.

Time-related bias

The JIF score is influenced by publication timing.

The measured 2-year window does not account for variance in publication processes among scientific fields.

The measured 2-year window does not account for the variation in citation rates among publication types and favors faster dissemination of “hot topics.”

Table 5 Disadvantages of the JIF [5–6, 10].

Table 1–5:  Jens C. Türp

German-speaking universities have also reacted in the meantime. For example, according to the habilitation regulations of the Medical Faculty of the Swiss University of Bern (dated November 2019), neither the journals in which candidates have published their work nor their respective JIF will be taken into account when evaluating their scientific performance [8]. Instead, the evaluation is based “on the scientific content of the work” [9]. Recently, no JIF may be listed in applications to the European Research Council either.

All these institutions are thus following the “San Francisco Decla­ration on Research Assessment” from 2012, which states as a general recommendation: “Do not use journal-based metrics, such as Journal Impact Factors, as a surrogate measure of the quality of individual research articles, to assess an individual scientist’s contributions, or in hiring, promotion, or funding decisions.” [2].

Conflict of interest

The author declares that there is no conflict of interest as defined by the guidelines of the International Committee of Medical Journal Editors.

References

  1. Asaad M, Kallarackal AP, Meaike J, Rajesh A, de Azevedo RU, Tran NV: Citation skew in plastic surgery journals: Does the Journal Impact Factor predict individual article citation rate? Aesthet Surg J 2020; 40: 1136–1142
  2. Cagan R: The San Francisco Decla­ra­tion on Research Assessment. Dis Model Mech 2013; 6: 869–870
  3. Garfield E: The history and meaning of the journal impact factor. JAMA 2006; 295: 90–93
  4. Kisslich T: Citation inequality and the Journal Impact Factor: median, mean, (does it) matter? Scientometrics 2021; 126: 1249–1269
  5. Mech E, Ahmed MM, Tamale E, Holek M, Li G, Thabane L: Evaluating Journal Impact Factor: a systematic survey of the pros and cons, and overview of alternative measures. J Venom Anim Toxins Incl Trop Dis 2020; 26: e20190082
  6. Nestor MS, Fischer DL, Arnold D, Berman B, Del Rosso JQ: Rethinking the Journal Impact Factor and publishing in the digital age. J Clin Aesthet Dermatol 2020; 13: 12–17
  7. Saginur M, Fergusson D, Zhang T, Yeates K, Ramsay T, Wells G, Moher D: Journal impact factor, trial effect size, and methodological quality appear scantly related: a systematic review and meta-analysis. Syst Rev 2020; 9: 53
  8. Steck N, Stalder L, Egger M: Journal- or article-based citation measure? A study of academic promotion at a Swiss university. F1000Res 2020; 9: 1188
  9. Universität Bern: Habilitationsreglement der Medizinischen Fakultät der Universität Bern vom November 2019. [URL: www.medizin.unibe.ch/unibe/portal/fak_medizin/content/e17203/e529687/e907140/200604_ Habilitationsreglement_Neuerlass_ def_ger.pdf; last access: September 1, 2021]
  10. University College London: Metrics to avoid – the impact factor. 2020. [URL: www.ucl.ac.uk/research/sites/ research/files/metrics_to_avoid_-_the_ impact_factor.pdf; last access: September 1, 2021]

Jens C. Türp

DDS, Dr med dent, MSc, M.A., Professor

Department of Oral Health & Medicine

University Center for Dental Medicine Basel UZB

Mattenstrasse 40

CH-4058 Basel, Switzerland

jens.tuerp@unibas.ch

Photo: Basilisk, Basel

 

 


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