How Many Scientists Fabricate and Falsify Research? A Systematic Review and Meta-Analysis of Survey Data

Abstract

The frequency with which scientists fabricate and falsify data, or commit other forms of scientific misconduct is a matter of controversy. Many surveys have asked scientists directly whether they have committed or know of a colleague who committed research misconduct, but their results appeared difficult to compare and synthesize. This is the first meta-analysis of these surveys.
To standardize outcomes, the number of respondents who recalled at least one incident of misconduct was calculated for each question, and the analysis was limited to behaviours that distort scientific knowledge: fabrication, falsification, “cooking” of data, etc… Survey questions on plagiarism and other forms of professional misconduct were excluded. The final sample consisted of 21 surveys that were included in the systematic review, and 18 in the meta-analysis.
A pooled weighted average of 1.97% (N = 7, 95%CI: 0.86–4.45) of scientists admitted to have fabricated, falsified or modified data or results at least once –a serious form of misconduct by any standard– and up to 33.7% admitted other questionable research practices. In surveys asking about the behaviour of colleagues, admission rates were 14.12% (N = 12, 95% CI: 9.91–19.72) for falsification, and up to 72% for other questionable research practices. Meta-regression showed that self reports surveys, surveys using the words “falsification” or “fabrication”, and mailed surveys yielded lower percentages of misconduct. When these factors were controlled for, misconduct was reported more frequently by medical/pharmacological researchers than others.
Considering that these surveys ask sensitive questions and have other limitations, it appears likely that this is a conservative estimate of the true prevalence of scientific misconduct.

Full text

How Many Scientists Fabricate and Falsify Research? A
Systematic Review and Meta-Analysis of Survey Data
Daniele Fanelli*
INNOGEN and ISSTI-Institute for the Study of Science, Technology & Innovation, The University of Edinburgh, Edinburgh, United Kingdom
Abstract
The frequency with which scientists fabricate and falsify data, or commit other forms of scientific misconduct is a matter of
controversy. Many surveys have asked scientists directly whether they have committed or know of a colleague who
committed research misconduct, but their results appeared difficult to compare and synthesize. This is the first meta-
analysis of these surveys. To standardize outcomes, the number of respondents who recalled at least one incident of
misconduct was calculated for each question, and the analysis was limited to behaviours that distort scientific knowledge:
fabrication, falsification, ‘‘cooking’’ of data, etc… Survey questions on plagiarism and other forms of professional
misconduct were excluded. The final sample consisted of 21 surveys that were included in the systematic review, and 18 in
the meta-analysis. A pooled weighted average of 1.97% (N =7, 95%CI: 0.86–4.45) of scientists admitted to have fabricated,
falsified or modified data or results at least once –a serious form of misconduct by any standard– and up to 33.7% admitted
other questionable research practices. In surveys asking about the behaviour of colleagues, admission rates were 14.12%
(N = 12, 95% CI: 9.91–19.72) for falsification, and up to 72% for other questionable research practices. Meta-regression
showed that self reports surveys, surveys using the words ‘‘falsification’’ or ‘‘fabrication’’, and mailed surveys yielded lower
percentages of misconduct. When these factors were controlled for, misconduct was reported more frequently by medical/
pharmacological researchers than others. Considering that these surveys ask sensitive questions and have other
limitations, it appears likely that this is a conservative estimate of the true prevalence of scientific misconduct.
Citation: Fanelli D (2009) How Many Scientists Fabricate and Falsify Research? A Systematic Review and Meta-Analysis of Survey Data. PLoS ONE 4(5): e5738.
doi:10.1371/journal.pone.0005738
Editor: Tom Tregenza, University of Exeter, United Kingdom
Received January 6, 2009; Accepted April 19, 2009; Published May 29, 2009
Copyright: ß2009 Fanelli. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: The author is supported by a Marie Curie Intra European Fellowship (Grant Agreement Number PIEF-GA-2008-221441). The funders had no role in
study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The author has declared that no competing interests exist.
* E-mail: dfanelli@staffmail.ed.ac.uk
Introduction
The image of scientists as objective seekers of truth is
periodically jeopardized by the discovery of a major scientific
fraud. Recent scandals like Hwang Woo-Suk’s fake stem-cell lines
[1] or Jan Hendrik Scho¨n’s duplicated graphs [2] showed how
easy it can be for a scientist to publish fabricated data in the most
prestigious journals, and how this can cause a waste of financial
and human resources and might pose a risk to human health. How
frequent are scientific frauds? The question is obviously crucial, yet
the answer is a matter of great debate [3,4].
A popular view propagated by the media [5] and by many
scientists (e.g. [6]) sees fraudsters as just a ‘‘few bad apples’’ [7]. This
pristine image of science is based on the theory that the scientific
community is guided by norms including disinterestedness and
organized scepticism, which are incompatible with misconduct
[8,9]. Increasing evidence, however, suggests that known frauds are
just the ‘‘tip of the iceberg’’, and that many cases are never
discovered. The debate, therefore, has moved on to defining the
forms, causes and frequency of scientific misconduct [4].
What constitutes scientific misconduct? Different definitions are
adopted by different institutions, but they all agree that fabrication
(invention of data or cases), falsification (wilful distortion of data or
results) and plagiarism (copying of ideas, data, or words without
attribution) are serious forms of scientific misconduct [7,10].
Plagiarism is qualitatively different from the other two because it
does not distort scientific knowledge, although it has important
consequences for the careers of the people involved, and thus for
the whole scientific enterprise [11].
There can be little doubt about the fraudulent nature of
fabrication, but falsification is a more problematic category.
Scientific results can be distorted in several ways, which can often
be very subtle and/or elude researchers’ conscious control. Data,
for example, can be ‘‘cooked’’ (a process which mathematician
Charles Babbage in 1830 defined as ‘‘an art of various forms, the
object of which is to give to ordinary observations the appearance
and character of those of the highest degree of accuracy’’[12]); it
can be ‘‘mined’’ to find a statistically significant relationship that is
then presented as the original target of the study; it can be
selectively published only when it supports one’s expectations; it
can conceal conflicts of interest, etc… [10,11,13,14,15]. Depend-
ing on factors specific to each case, these misbehaviours lie
somewhere on a continuum between scientific fraud, bias, and
simple carelessness, so their direct inclusion in the ‘‘falsification’’
category is debatable, although their negative impact on research
can be dramatic [11,14,16]. Henceforth, these misbehaviours will
be indicated as ‘‘questionable research practices’’ (QRP, but for a
technical definition of the term see [11]).
Ultimately, it is impossible to draw clear boundaries for
scientific misconduct, just as it is impossible to give a universal
definition of professional malpractice [10]. However, the intention
to deceive is a key element. Unwilling errors or honest differences
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in designing or interpreting a research are currently not considered
scientific misconduct [10].
To measure the frequency of misconduct, different approaches
have been employed, and they have produced a corresponding
variety of estimates. Based on the number of government
confirmed cases in the US, fraud is documented in about 1 every
100.000 scientists [11], or 1 every 10.000 according to a different
counting [3]. Paper retractions from the PubMed library due to
misconduct, on the other hand, have a frequency of 0.02%, which
led to speculation that between 0.02 and 0.2% of papers in the
literature are fraudulent [17]. Eight out of 800 papers submitted to
The Journal of Cell Biology had digital images that had been
improperly manipulated, suggesting a 1% frequency [11]. Finally,
routine data audits conducted by the US Food and Drug
Administration between 1977 and 1990 found deficiencies and
flaws in 10–20% of studies, and led to 2% of clinical investigators
being judged guilty of serious scientific misconduct [18].
All the above estimates are calculated on the number of frauds
that have been discovered and have reached the public domain.
This significantly underestimates the real frequency of misconduct,
because data fabrication and falsification are rarely reported by
whistleblowers (see Results), and are very hard to detect in the data
[10]. Even when detected, misconduct is hard to prove, because
the accused scientists could claim to have committed an innocent
mistake. Distinguishing intentional bias from error is obviously
difficult, particularly when the falsification has been subtle, or the
original data destroyed. In many cases, therefore, only researchers
know if they or their colleagues have wilfully distorted their data.
Over the years, a number of surveys have asked scientists
directly about their behaviour. However, these studies have used
different methods and asked different questions, so their results
have been deemed inconclusive and/or difficult to compare (e.g.
[19,20]). A non-systematic review based on survey and non-survey
data led to estimate that the frequency of ‘‘serious misconduct’’,
including plagiarism, is near 1% [11].
This study provides the first systematic review and meta-analysis
of survey data on scientific misconduct. Direct comparison
between studies was made possible by calculating, for each survey
question, the percentage of respondents that admitted or observed
misconduct at least once, and by limiting the analysis to
qualitatively similar forms of misconduct -specifically on fabrica-
tion, falsification and any behaviour that can distort scientific data.
Meta-analysis yielded mean pooled estimates that are higher than
most previous estimates. Meta-regression analysis identified key
methodological variables that might affect the accuracy of results,
and suggests that misconduct is reported more frequently in
medical research.
Methods
Searching
Electronic resources were searched during the first two weeks of
August 2008. Publication and journal databases were searched in
English, while the Internet and resources for unpublished and
‘‘grey’’ literature were searched using English, Italian, French and
Spanish words.
Citation databases. The Boolean string ‘‘research
misconduct’’ OR ‘‘research integrity’’ OR ‘‘research
malpractice’’ OR ‘‘scientific fraud’’ OR ‘‘fabrication,
falsification’’ OR ‘‘falsification, fabrication’’ was used to search:
Science Citation Index Expanded (SCI-EXPANDED), Social
Sciences Citation Index (SSCI), Arts & Humanities Citation Index
(A&HCI), Conference Proceedings Citation Index- Science
(CPCI-S), BIOSIS Previews, MEDLINE, Business Source
Premier, CINAHL Plus, SPORTDiscus, Library, Information
Science & Technology Abstracts, International Bibliography of the
Social Sciences, America: History & Life, Teacher Reference
Center, Applied Social Sciences Index And Abstracts (ASSIA),
ERIC, Index Islamicus, CSA linguistics and language behaviour,
Physical Education Index, PILOTS, Social Services Abstracts,
Sociological Abstracts, Proquest Dissertation & Theses,
ECONLIT, Educational Research Abstracts (ERA) Online,
Article First, Economic and Social Data Service, Francis,
Geobase, Georefs, Global Health (CABI), Index to Theses,
International Bibliography of the Social Sciences (IBSS), IEEE
Xplore, INSPEC, JSTOR, Mathematical Sciences Net
(MathSciNet), PubMEd, Russian Academy of Sciences
bibliographies, Sciencedirect, Teacher Reference Center,
EMBASE, EMBASE Classics, PSYCHINFO.
Scientific journals. The Boolean string ‘‘research misconduct’’
OR ‘‘research integrity’’ OR ‘‘research malpractice’’ OR ‘‘scientific
fraud’’ OR ‘‘fabrication, falsification’’ OR ‘‘falsification, fabrication’’
was used to search: Interdisciplinary Science Reviews, American
Journal of Sociology, Annual Review of Sociology, PNAS, Issues in
Science & Technology, Journal of Medical Ethics, PLoSONE,
Science and Engineering Ethics, Sociology of Health & Illness,
Minerva, The Scientific World Journal, Social Science Research,
Social Studies of Science, Science in Context.
Grey literature databases. The Boolean string ‘‘research
misconduct’’ OR ‘‘research integrity’’ OR ‘‘research malpractice’’
OR ‘‘scientific fraud’’ OR ‘‘fabrication, falsification’’ OR
‘‘falsification, fabrication’’ was used to search: SIGLE, National
Technical Information Service, British Library Collections, British
Library Direct, Canadian Evaluation Society, Bioethics Literature
Database.
The Italian string ‘‘etica AND ricerca’’ was used in: CNR
database.
The French string ‘‘scientifique AND ‘‘ethique’’ OR ‘‘fraude’’
OR ‘‘faute’’ OR ‘‘enquete’’ OR ‘‘sondage’’ was used in: LARA -
Libre acces aux rapports scientifiques et techiques
Internet search engines. The Boolean string ‘‘research
misconduct’’ OR ‘‘research integrity’’ OR ‘‘research
malpractice’’ OR ‘‘scientific fraud’’ OR ‘‘fabrication,
falsification’’ OR ‘‘falsification, fabrication’’, the Spanish
Boolean string ‘‘e´tica cientifica’’ OR ‘‘faltas e´ticas’’ the French
Boolean string ‘‘faute scientifique’’ OR ‘‘e´thique scientifique’’ were
used to search: ScienceResearch.com, Scirus.
Titles and available abstracts of all records were examined, and
the full text of all potentially relevant studies was retrieved. The
references list of the retrieved studies and of other documents was
also examined in search of potentially relevant papers.
Selection
Only quantitative survey data assessing how many researchers
have committed or observed colleagues committing scientific
misconduct in the past were included in this review. Surveys asking
only opinions or perceptions about the frequency of misconduct
were not included.
To allow direct quantitative comparison across data sets, studies
were included only if they presented data in frequency or
percentage categories, one of which was a ‘‘never’’ or ‘‘none’’ or
‘‘nobody’’ category - indicating that the respondent had never
committed or observed the behaviour in question. Studies lacking
such a category, or presenting results in statistical formats that
prevented the retrieval of this information (e.g. mean and standard
deviation) were excluded. Respondents of any professional position
and scientific discipline were included, as long as they were
actively conducting publishable research, or directly involved in it
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(e.g. research administrators). Surveys addressing misconduct in
undergraduate students were excluded, because it was unclear if
the misconduct affected publishable scientific data or only
scholastic results.
This review focused on all and only behaviours that can falsify
or bias scientific knowledge through the unjustified alteration of
data, results or their interpretation (e.g. any form of fabrication
and falsification, intentional non-publication of results, biased
methodology, misleading reporting, etc…). Plagiarism and profes-
sional misconduct (e.g. withholding information from colleagues,
guest authorship, exploitation of subordinates etc…) were
excluded from this review. Surveys that made no clear distinction
between the former and latter types of misconduct (e.g. that asked
about fabrication, falsification and plagiarism in the same
question) were excluded.
Any available data on scientists’ reaction to alleged cases of
misconduct was extracted from included studies. Since these data
provided only additional information that was not the focus of the
review, survey questions that did not distinguish between data
manipulation and plagiarism were included in this section of the
results, but clearly identified.
Validity assessment
Surveys that did not sample respondents at random, or that did
not provide sufficient information on the sampling methods
employed where given a quality score of zero and excluded from
the meta-analysis. All remaining papers were included, and were
not graded on a quality scale, because the validity and use of
quality measures in meta-analysis is controversial [21,22]. Instead
of using an arbitrary measure of quality, the actual effect of
methodological characteristics on results was tested and then
controlled for with regression analysis. In the tables listing study
characteristics, the actual words reported in the paper by the
authors are quoted directly whenever possible. The few cases
where a direct quotation could not be retrieved are clearly
indicated.
Data abstraction
For each question, the percentage of respondents who recalled
committing or who observed (i.e. had direct knowledge of) a
colleague who committed one or more times the specified
behaviour was calculated. In the majority of cases, this required
summing up the responses in all categories except the ‘‘none’’ or
‘‘never’’ category, and the ‘‘don’t know’’ category.
Some studies subdivided the sample of respondents according to
a variety of demographic characteristics (e.g. gender, career level,
professional position, academic discipline, etc…) and disaggregat-
ed the response data accordingly. In all these cases, the data was
re-aggregated.
Given the objectivity of the information collected and the fact
that all details affecting the quality of studies are reported in this
paper, it was not necessary to have the data extracted/verified by
more than one person.
Quantitative data synthesis
The main outcome of the meta-analysis was the percentage
(proportion) of respondents that recalled committing or that knew
of a colleague committing the specified behaviour at least once in
the given recall period. This measure was not normally distributed
(Kolmogorov-Smirnov test: 0.240, df = 19, P = 0.005) so it was logit
transformed [23], and weighted by inverse variance of logit
transformed proportion using the following equations for effect
size, standard error and weight, respectively:
ES~Loge
p
1{pðÞ

SE~ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
1
np z1
n1{pðÞ
s
W~1
SE2~np 1{pðÞ
Where pis the proportion of respondents recalling at least one case
of the specified behaviour, and n is the total number of
respondents. The distribution of the logit-transformed effect sizes
was not significantly different from normal (K-S: 0.109, df = 19,
P = 0.2). To facilitate their interpretation, the final logit results (ES
and 95%CI) were back-transformed in percentages using the
following equations for proportion and percentages, respectively:
p~ex
exz1
%~100p
Where xis either ES or each of the corresponding 95%CI values.
Mean pooled effect size was calculated assuming a random
effects model, and homogeneity was tested with Chochran’s Q
test. Differences between groups of studies were tested using
inverse variance weighted one-way ANOVA. The combined effect
of independent variables on effect sizes was tested with inverse
variance weighted regression assuming a random effects model
and estimated via iterative maximum likelihood.
To avoid the biasing effect of multiple outcomes within the same
study, all meta-analyses on the main outcome of interest (i.e. the
prevalence of data fabrication, falsification and alteration) were
conducted using only one outcome per study. For the same reason,
in the regression analysis, which combined all available effect sizes
on data fabrication, falsification and alteration, studies that had
data both on self- and on non self- where used only for the former.
The regression model first tested the combined effect of three
methodological factors measured by binary variables (self- vs non-
self- reports, handed vs mailed questionnaire, questions using the
word ‘‘falsification’’ or ‘‘fabrication’’ vs questions using ‘‘alter-
ation’’, ‘‘modification’’ etc…). Then, the effect of several study
characteristics was tested (year when the survey was conducted,
surveys conducted in the USA vs anywhere else, surveys
conducted exclusively on researchers vs any other, biomedical vs
other types of research, social sciences vs natural sciences, medical
consultants and practitioners vs other). To avoid over-fitting, each
study characteristic was tested independently of the others.
Questions on behaviours of secondary interest (questionable
research practices) where too diverse to allow meaningful meta-
analysis, so they were combined in broad categories for which only
crude unweighted parameters were calculated. All statistical
analyses were run on SPSS software package. Meta-analyses were
conducted using the ‘‘MeanES’’, ‘‘MetaF’’ and ‘‘MetaReg’’
macros by David B. Wilson [24].
Publication bias-Sensitivity analysis
The popular funnel-plot-based methods to test for publication
bias in meta-analysis are inappropriate and potentially misleading
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when the number of included studies is small and heterogeneity is
large [25,26]. However, the robustness of results was assessed with
a sensitivity analysis. Pooled weighted estimates for effect size and
regression parameters were calculated leaving out one study at a
time, and then compared to identify influential studies. In
addition, to further assess the robustness of conclusions, meta-
analyses and meta-regression were run without logit transforma-
tion.
Results
Flow of included studies
Electronic search produced an initial list of 3276 references.
Examination of titles and abstracts, and further examination of the
references lists in the retrieved papers and in other sources led to a
preliminary list of 69 potentially relevant studies. Of these, 61 were
published in peer-reviewed journals, three were dissertations
theses, three were published in non-peer reviewed popular science
magazines, one was published in a book chapter, and one was
published in a report. All studies were published in English except
for one in Spanish.
After examination of full text, 33 studies were excluded because
they did not have any relevant or original data, two because they
presented data exclusively in a format that could not be used in
this review (e.g. means and standard deviations), eight because
their sample included non-researchers (e.g. students) and/or
because they addressed forms of academic misconduct not directly
related to research (e.g. cheating on school projects), five because
they do not distinguish fabrication and falsification from types of
misconduct not relevant to the scopes of this review (Table S1).
Therefore, 21 studies were included in the review. Three of these
did not match the quality requirements to be included in the meta-
analysis. Data from these three studies was only used to estimate
crude unweighted means for QRP and more generic questions,
and not for analyzing the main outcome of interest (data
fabrication, falsification, modification). Therefore, the meta-
analysis was conducted on 18 studies (Figure 1).
Study characteristics
Table 1 lists the characteristics of included studies and their
quality score for inclusion in meta-analysis. Included surveys were
published between 1987 and 2008, but had been conducted
between 1986 ca and 2005. Respondents were based in the United
States in 15 studies (71% ca of total), in the United Kingdom in 3
studies (14% ca), two studies had a multi-national sample (10% ca)
and one study was based in Australia. Six studies had been
conducted among biomedical researchers, eight were more
specifically targeted at researchers holding various positions in
the medical/clinical sciences (including pharmacology, nursing,
health education, clinical biostatistics, and addiction-studies), six
surveys had multi-disciplinary samples, one surveyed economists.
Quantitative data analysis
Scientists admitting misconduct. When explicitly asked if
they ever fabricated or falsified research data, or if they altered or
modified results to improve the outcome (see Table S2, questions
1, 4, 6, 8, 10, 17, 26), between 0.3% and 4.9% of scientists replied
affirmatively (N = 7, crude unweighted mean: 2.59%,
95%CI = 1.06–4.13). Meta-analysis yielded a pooled weighted
Figure 1. Study selection flow diagram.
doi:10.1371/journal.pone.0005738.g001
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Table 1. Characteristics of studies included in the review.
ID Date Country Sample Method N (%) Self-/Non self- Quality
Tangney, 1987 [32] n.s US Researchers in a ‘‘highly ranked American university’’. Distributed within department 245 (22) n 1
Lock, 1988 [29] 1988 UK Professors of medicine or surgery, other academics, doctors,
research managers, editors of medical journals non-randomly
contacted by the author
Mailed+pre-paid return 79 (98.7) n 0
Simmons, 1991 [54] 1989 US Active members of the Society of University Surgeons n.s. 202 (82) n 0
Kalichman, 1992 [35] 1990 US Research trainees in the clinical and basic biomedical sciences
at the University of California, San Diego
Distributed through the department 549 (27) s+n1
Swazey, 1993 [53] 1990 US Doctoral students and faculty, from 99 of the largest graduate
departments in chemistry, civil engineering, microbiology and
sociology
Mailed+prepaid return+postcard to confirm
response
2620 (65.5) n 1
Glick, 1993 [55] 1992 US Biotechnology companies’ executives known by the author Administered orally, on the phone 15* (n.s) n 0
Greenberg, 1994 [20] 1991 US Members of the Society for Risk Analysis, Association of
Environmental and Resource Economists, American Industrial
Hygiene Association
Mailed 478 (32) n 1
Glick, 1994 [30] 1993 US Attendees at the Third Conference on Research Policies and
Quality Assurance
Handed out, personally returned by
respondents on the same
36 (34) n 1
Eastwood, 1996 [56] 1993 US All postdoctoral fellows registered with the Office of Research
Affairs of the University of California, San Francisco
Mailed+follow-up letter 324 (32.8) s+n1
Bebeau, 1996 [33] 1995 US Program chairs and officers of the American Association for Dental
Research
Mailed+prepaid return+postcard to confirm
response
76 (78) n 1
Rankin, 1997 [57] 1995 US Research coordinators or directors of master’s and doctoral
nursing programs
Mailed 88 (43) n 1
May, 1998 [34] 1997 UK Randomly selected authors of papers published in the past
3 years on addiction-related subjects
Mailed 36 (51) n 1
Ranstam, 2000 [46] 1998 Various Members of the International Society of Clinical Biostatistics Mailed+online electronic version 163 (37) n 1
List, 2001 [28] 1998 US Participants to the January 1998 meetings of the American
Economic Association
Hand-delivered, Direct Response+Random
Response method, drop box for returning
responses
94 (23.5) s 1
Geggie, 2001 [58] 2000 UK Medical consultants appointed between Jan 1995 and Jan 2000
working in 7 hospital trusts in the Mersey region
Mailed+pre-paid return 194 (63.6) s+n1
Meyer, 2004 [59] n.s US Members of editorial boards of American Accounting Association
journals, and participants at the 1998, 1999, and 2000 American
Accounting Association New Faculty Consortia
Email asking to reply if unwilling to
participate, mailed+pre-paid return
176 (48.5) n 1
Martinson, 2005 [19] 2002 US Researchers funded by the National Institutes of Health Mailed, pre-paid return, 2$ 3247 (47.2) s 1
Henry, 2005 [60] 2002 Australia Medical specialists, from the 2002 edition of the Medical directory
of Australia, involved in pharmaceutical industry-sponsored research
Mailed 338* (n.a.) s 1
Gardner, 2005 [27] 2002 Various Authors of pharmaceutical clinical trials published in the Cochrane
Database of Systematic Reviews, equally selected between first,
middle and last author.
Mailed+10$ check+second survey to
non-respondents+follow-up call or email
322 (64) s+n1
Kattenbraker 2007 [61] 2005 US Health education professors at every rank, teaching at 94
institution of higher education
Email+web-based survey+follow up email+final
reminder
153 (25.8) n 1
Titus, 2008 [31] 2005 US Researchers funded by the National Institutes of Health, one per
department
Pre-notification+mailed+reminder
postcard+additional survey packet+follow-up letter
2212 (52) n 1
Abbreviations: ‘‘Date’’ is the year when the survey was actually conducted, ‘‘N’’ is the number of respondents who returned the questionnaire, ‘‘%’’ is the response rate of the survey.
*
Number of respondents who ad engaged in industry-sponsored research in the previous 12 months, out of a total sample of 2253, with 39% response rate.
doi:10.1371/journal.pone.0005738.t001
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estimate of 1.97% (95%CI: 0.86–4.45), with significant
heterogeneity (Cochran’s Q = 61.7777, df = 6, P,0.0001)
(Figure 2). If only questions explicitly using the words
‘‘fabrication’’ or ‘‘falsification’’ were included (Table S2,
questions 3, 6, 10, 26), the pooled weighted estimate was 1.06%
(N = 4, 95%CI: 0.31–3.51)
Other questionable practices were admitted by up to 33.7% of
respondents (Table S2) (Figure 3, N = 20 (six studies), crude
unweighted mean: 9.54%, 95%CI = 5.15–13.94).
Consistently across studies, scientists admitted more frequently
to have ‘‘modified research results’’ to improve the outcome than
to have reported results they ‘‘knew to be untrue’’ (Inverse
Variance Weighted Oneway ANOVA Q(1,4) = 14.8627,
P = 0.011)
In discussing limitations of results, two studies [19,27] suggested
that their results were very conservative with respect to the actual
occurrence of misconduct, while the other studies made no clear
statement. Non-response bias was recognized as a limitation by
most surveys. One study employed a Random-Response technique
on part of its sample to control for non-response bias, and found
no evidence for it [28] (see Discussion for further details).
Scientists observing misconduct. When asked if they had
personal knowledge of a colleague who fabricated or falsified
research data, or who altered or modified research data (Table S3,
questions, 1, 6, 7, 10, 20, 21, 29, 32, 34, 37, 45, 54) between 5.2%
and 33.3% of respondents replied affirmatively (N = 12, crude
unweighted mean: 16.66%, 95%CI = 9.91–23.40). Meta-analysis
yielded a pooled weighted estimate of 14.12% (95% CI: 9.91–
19.72) (Figure 4). If only questions explicitly using the words
‘‘fabrication’’ or ‘‘falsification’’ were included (Table S3, questions
1, 6, 7, 10, 17, 21, 29, 32, 37, 45, 54), the pooled weighted estimate
was 12.34% (N = 11, 95%CI: 8.43–17.71)
Between 6.2% and 72% of respondents had knowledge of
various questionable research practices (Table S3) (Figure 3,
Figure 2. Forrest plot of admission rates of data fabrication,
falsification and alteration in self reports. Area of squares
represents sample size, horizontal lines are 95% confidence interval,
diamond and vertical dotted line show the pooled weighted estimate.
doi:10.1371/journal.pone.0005738.g002
Figure 3. Admission rates of Questionable Research Practices
(QRP) in self- and non-self-reports. N indicates the number of
survey questions. Boxplots show median and interquartiles.
doi:10.1371/journal.pone.0005738.g003
Figure 4. Forrest plot of admission rates of data fabrication,
falsification and alteration in non-self reports. Area of squares
represents sample size, horizontal lines are 95% confidence interval,
diamond and vertical dotted line show the pooled weighted estimate.
doi:10.1371/journal.pone.0005738.g004
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N = 23 (6 studies), crude unweighted mean: 28.53%,
95%CI = 18.85–38.2). When surveys asked about more generic
questions (e.g. ‘‘do you have knowledge of any cases of fraud?’’
[29,30]) or defined misconduct in more comprehensive ways (e.g.
‘‘experimental deficiencies, reporting deficiencies, misrepresenta-
tion of data, falsification of data’’ [30]) between 12% and 92%
replied affirmatively (Table S3) (N = 10 (seven studies), crude
unweighted mean: 46.24, 95%CI = 16.53–75.95).
In discussing their results, three studies [27,29,31] considered
them to be conservative, four [30,32,33,34] suggested that they
overestimated the actual occurrence of misconduct, and the
remaining 13 made no clear statement.
Scientists reporting misconduct. Five of the included
studies asked respondents what they had done to correct or
prevent the act of misconduct they had witnessed. Around half of
the alleged cases of misconduct had any action taken against them
(Table 2). No study asked if these actions had the expected
outcome. One survey [27] found that 29% of the cases of
misconduct known by respondents were never discovered.
Factors influencing responses. Methodological differences
between studies explained a large portion of the variance among
effect sizes (N = 15, one outcome per study, Table 3). Lower
percentages of misconduct were reported in self reports, in surveys
using the words ‘‘falsification’’ or ‘‘fabrication’’, and in mailed
surveys. Mailed surveys had also higher response rates than
handed-out surveys (Mean: 26.63%62.67SE and
48.53%64.02SE respectively, t-test: t = 22.812, df = 16,
P = 0.013), while no difference in response rates was observed
between self- and non-self-reports (Mean: 42.4466.24SE and
44.4465.1SE respectively, t = 20.246, P = 0.809) and between
surveys using or not ‘‘fabrication or falsification’’ (Mean:
42.98%66.0SE and 44.5164.76SE respectively, t = 20.19,
P = 0.85). Excluding all surveys that were not mailed, were not
self-reports and that did not use the words ‘‘falsification’’ or
‘‘fabrication’’ yielded a maximally conservative pooled weighted
estimate of 0.64% (N = 3, 95%CI: 0.25–1.63).
When the three methodological factors above where controlled
for, a significant effect was found for surveys targeted at medical
and clinical researchers, who reported higher percentages of
misconduct than respondents in biomedical research and other
fields (Table 3). The effect of this parameter would remain
significant if Bonferroni-corrected for multiple comparisons. If self-
Table 2. Actions taken against misconduct.
ID N cases Action taken %
Tangney, 1987 [32] 78 Took some action to verify their suspicions of fraud or to remedy the situation 46
Rankin, 1997 [57] 31 [ffp] In alleged cases of scientific misconduct a disciplinary action was taken by the dean 32.4
Some authority was involved in a disciplinary action 20.5
Ranstam, 2000 [46] 49 I interfered to prevent it from happening 28.6
I reported it to a relevant person or organization 22.4
Kattenbraker, 2007 [61] 33 Confronted individual 55.5
Reported to supervisor 36.4
Reported to Institutional Review Board 12.1
Discussed with colleagues 36.4
Titus, 2008 [31] 115 [ffp] The suspected misconduct was reported by the survey respondent 24.4
The suspected misconduct was reported by someone else 33.3
Abbreviations: ‘‘N cases’’ is the total number of cases of misconduct observed by respondents, [ffp] indicates that the number includes cases of plagiarism, ‘‘%’’ is the
percentage of cases that had the specified action taken against them. All responses are mutually exclusive except in Kattenbraker 2007.
doi:10.1371/journal.pone.0005738.t002
Table 3. Inverse variance-weighted regression on admission rates.
Variable B6SE P Stand. Coeff. Model R
2
Base Model Constant 24.5360.81 ,0.0001 0 0.82
Self-/Non-self 23.0260.38 ,0.0001 21.04
Mailed/Handed 21.1760.4 0.0032 20.33
‘‘Fabricated, Falsified’’/‘‘Modified’’ 21.0260.39 0.0086 20.34
Candidate co-variables Year 20.0360.03 0.3 20.14 0.83
USA/other 20.7160.4 0.08 20.2 0.85
Researcher/other 20.3360.33 0.32 20.11 0.83
Biomedical/other 0.1760.39 0.66 0.06 0.82
Medical/other 0.8560.28 0.0022 0.29 0.89
Social Sc./other 20.0360.37 0.94 20.01 0.82
The table shows model parameters of an initial model including three methodological factors (top four rows) and the parameter values for each sample characteristic,
entered one at a time in the basic model. All variables are binary. Regression slopes measure the change in admission rates when respondents fall in the first category.
doi:10.1371/journal.pone.0005738.t003
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and non-self- reports were tested separately for the effect of study
characteristics (one characteristic at a time), a significant effect was
found only in self-reports for year when survey was conducted
(k = 7, b = 20.142560.0519, P = 0.006) and a nearly significant
effect was found again in self-reports for survey delivery method
(k = 7, b = 21.249660.6382, P = 0.0502)
Sensitivity analysis
Self-report admission rates varied between 1.65% -following the
removal of Kalichman and Friedman (1992) [35]- and 2.93% -
following the removal of Martinson et al. (2005) [19] (Figure 5).
Reports on colleagues’ misconduct varied between 12.85% (when
Tangney (1987) [32] was removed) and 15.41% (when Titus et al.
(2008) [31] was removed (Figure 6). Weighted pooled estimates on
non-logit-trasformed data yielded self- and non-self- admission
rates of 2.33% (95%CI 0.94–3.73%) and 14.48% (95%CI: 11.14–
17.81%) respectively, showing that the results are robust and
conservative.
Results of the regression analysis were robust to the leave-one-
study-out test: the four significant variables remained statistically
significant when anyone of the studies was excluded (Table S4).
The largest portion of variance was explained when Titus et al.
(2008) [31] was removed (R
2
= 0.9202). Meta-regression on non-
transformed data showed similar trends to that on transformed
data for all four parameters, but only two parameters remained
statistically significant (self-/non-self- and delivery method,
P,0.0001 and p = 0.0083 respectively), and the overall portion
of variance explained by the model was lower (R
2
= 0.6904).
Discussion
This is the first meta-analysis of surveys asking scientists about
their experiences of misconduct. It found that, on average, about
2% of scientists admitted to have fabricated, falsified or modified
data or results at least once –a serious form of misconduct my any
standard [10,36,37]– and up to one third admitted a variety of
other questionable research practices including ‘‘dropping data
points based on a gut feeling’’, and ‘‘changing the design,
methodology or results of a study in response to pressures from
a funding source’’. In surveys asking about the behaviour of
colleagues, fabrication, falsification and modification had been
observed, on average, by over 14% of respondents, and other
questionable practices by up to 72%. Over the years, the rate of
admissions declined significantly in self-reports, but not in non-self-
reports.
A large portion of the between-studies variance in effect size was
explained by three basic methodological factors: whether the
survey asked about self or not, whether it was mailed or handed
out to respondents, and whether it explicitly used the words
‘‘fabrication’’ and ‘‘falsification’’. Once these factors were
controlled for, surveys conducted among clinical, medical and
pharmacological researchers appeared to yield higher rates of
misconduct than surveys in other fields or in mixed samples.
All the above results were robust with respect to inclusion or
exclusion of any particular study, with perhaps one exception:
Martinson et al. (2005) [19], which is one of the largest and most
frequently cited surveys on misconduct published to date. This
study appears to be rather conservative, because without it the
pooled average frequency with which scientists admit they have
committed misconduct would jump to nearly 3%.
Figure 5. Sensitivity analysis of admission rates of data
fabrication, falsification and alteration in self reports. Plots
show the weighted pooled estimate and 95% confidence interval
obtained when the corresponding study was left out of the analysis.
doi:10.1371/journal.pone.0005738.g005
Figure 6. Sensitivity analysis of admission rates of data
fabrication, falsification and alteration in non-self reports.
Plots show the weighted pooled estimate obtained when the
corresponding study was left out of the analysis.
doi:10.1371/journal.pone.0005738.g006
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How reliable are these numbers? And what can they tell us on
the actual frequency of research misconduct? Below it will be
argued that, while surveys asking about colleagues are hard to
interpret conclusively, self-reports systematically underestimate the
real frequency of scientific misconduct. Therefore, it can be safely
concluded that data fabrication and falsification –let alone other
questionable research practices- are more prevalent than most
previous estimates have suggested.
The procedure adopted to standardize data in the review clearly
has limitations that affect the interpretation of results. In particular,
the percentage of respondents that recall at least one incident of
misconduct is a very rough measure of the frequency of misconduct,
because some of the respondents might have committed several
frauds, but others might have ‘‘sinned’’ only once. In this latter case,
the frequencies reported in surveys would tend to overestimate the
prevalence of biased or falsified data in the literature. The history of
science, however, shows that those responsible of misconduct have
usually committed it more than once [38,39], so the latter case
might not be as likely as the former. In any case, many of the
included studies asked to recall at least one incident, so this
limitation is intrinsic to large part of the raw data.
The distinction made in this review between ‘‘fabrication,
falsification and alteration’’ of results and QRP is somewhat
arbitrary. Not all alterations of data are acts of falsification, while
‘‘dropping data points based on a gut feeling’’ or ‘‘failing to publish
data that contradicts one’s previous research’’ (e.g. [19]) might
often be. As explained in the introduction, any boundary defining
misconduct will be arbitrary, but intention to deceive is the key
aspect. Scientists who answered ‘‘yes’’ to questions asking if they
ever fabricated or falsified data are clearly admitting their
intention to misrepresent results. Questions about altering and
modifying data ‘‘to improve the outcome’’ might be more
ambiguously interpreted, which might explain why these questions
yield higher admission rates. However, even if we limited the
meta-analysis to the most restrictive types of questions in self-
reports, we would still have an average admission rate above 1%,
which is higher than previous estimates (e.g. [11]).
The accuracy of self-reports on scientific misconduct might be
biased by the effect of social expectations. In self-reports on
criminal behaviour, social expectations make many respondents
less likely to admit a crime they committed (typically, females and
older people) and make others likely to report a crime they have
not really committed (typically, young males) [40]. In the case of
scientists, however, social expectations should always lead to
underreporting, because a reputation of honesty and objectivity is
fundamental in any stage of a scientific career. Anyone who has
ever falsified research is probably unwilling to reveal it and/or to
respond to the survey despite all guarantees of anonymity [41].
The opposite (scientists admitting misconduct they didn’t do)
appears very unlikely. Indeed, there seems to be a large
discrepancy between what researchers are willing to do and what
they admit in a survey. In a sample of postdoctoral fellows at the
University of California San Francisco, USA, only 3.4% said they
had modified data in the past, but 17% said they were ‘‘willing to
select or omit data to improve their results’’ [42]. Among research
trainees in biomedical sciences at the University of California San
Diego, 4.9% said they had modified research results in the past,
but 81% were ‘‘willing to select, omit or fabricate data to win a
grant or publish a paper’’ [35].
Mailed surveys yielded lower frequencies of misconduct than
handed out surveys. Which of the two is more accurate? Mailed
surveys were often combined with follow-up letters and other
means of encouraging responses, which ensured higher response
rates. However, the accuracy of responses to sensitive questions is
often independent of response rates, and depends strongly on
respondents’ perception of anonymity and confidentiality [43,44].
Questionnaires that are handed to, and returned directly by
respondents might better entrust anonymity than surveys that need
to be mailed or emailed. Therefore, we cannot rule out the
possibility that handed out surveys are more accurate despite the
lower response rates. This latter interpretation would be supported
by one of the included studies: a handed out survey that attempted
to measure non-response bias using a Random-Response (RR)
technique on part of its sample [28]. Differently from the usual
Direct Response technique, in RR, respondents toss coins to
determine whether they will respond to the question or just mark
‘‘yes’’. This still allows admission rates to be calculated, yet it
guarantees full anonymity to respondents because no one can tell
whether an individual respondent answered ‘‘yes’’ to the question
or because of chance. Contrary to author’s expectations, response
and admission rates were not higher with RR compared to DR,
suggesting that in this handed out survey non-response bias was
absent.
The effect of social expectations in surveys asking about
colleagues is less clear, and could depend on the particular interests
of respondents. In general, scientists might tend to protect the
reputation of their field, by minimizing their knowledge of
misconduct [27]. On the other hand, certain categories of
respondents (e.g. participants at a Conference on Research Policies
and Quality Assurance [30]) might have particular experience with
misconduct and might be very motivated to report it.
Surveys on colleagues’ behaviour might tend to inflate estimates
of misconduct also because the same incident might be reported by
many respondents. One study controlled for this factor by asking
only one researcher per department to recall cases that he had
observed in that department in the past three years [31]. It found
that falsification and fabrication had been observed by 5.2% of
respondents, which is lower than all previous non-self reports.
However, since one individual will not be aware of all cases
occurring around him/her, this is a conservative estimate [31]. In
the sensitivity analysis run on the regression model, exclusion of
this study caused the single largest increase in explained variance,
which further suggests that findings of this study are unusual.
Another critical factor in interpreting survey results is the
respondents’ perception of what does and does not constitute
research misconduct. As mentioned before, scientists were less
likely to reply affirmatively to questions using the words
‘‘fabrication’’ and ‘‘falsification’’ rather than ‘‘alteration’’ or
‘‘modification’’. Moreover, three surveys found that scientists
admitted more frequently to have ‘‘modified’’ or ‘‘altered’’
research to ‘‘improve the outcome’’ than to have reported results
they ‘‘knew to be untrue’’. In other words, many did not think that
the data they ‘‘improved’’ were falsified. To some extent, they
were arguably right. But the fuzzy boundary between removing
noise from results and biasing them towards a desired outcome
might be unknowingly crossed by many researchers [10,14,45]. In
a sample of biostatisticians, who are particularly well trained to see
this boundary, more than half said they had personally witnessed
false or deceptive research in the preceding 10 years [46].
The grey area between licit, questionable, and fraudulent
practices is fertile ground for the ‘‘Mohammed Ali effect’’, in which
people perceive themselves as more honest than their peers. This
effect was empirically proven in academic economists [28] and in a
large sample of biomedical researchers (in a survey assessing their
adherence to Mertonian norms [47]), and may help to explain the
lower frequency with which misconduct is admitted in self-reports:
researchers might be overindulgent with their behaviour and
overzealous in judging their colleagues. In support of this, one study
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found that 24% of cases observed by respondents did not meet the
US federal definition of research misconduct [31].
The decrease in admission rates observed over the years in self-
reports but not in non-self-reports could be explained by a
combination of the Mohammed Ali effect and social expectations.
The level and quality of research and training in scientific integrity
has expanded in the last decades, raising awareness among
scientists and the public [11]. However, there is little evidence that
researchers trained in recognizing and dealing with scientific
misconduct have a lower propensity to commit it [47,48,49].
Therefore, these trends might suggest that scientists are no less
likely to commit misconduct or to report what they see their
colleagues doing, but have become less likely to admit it for
themselves.
Once methodological differences were controlled for, cross-
study comparisons indicated that samples drawn exclusively from
medical (including clinical and pharmacological) research reported
misconduct more frequently than respondents in other fields or in
mixed samples. To the author’s knowledge, this is the first cross-
disciplinary evidence of this kind, and it suggests that misconduct
in clinical, pharmacological and medical research is more
widespread than in other fields. This would support growing fears
that the large financial interests that often drive medical research
are severely biasing it [50,51,52]. However, as all survey-based
data, this finding is open to the alternative interpretation that
respondents in the medical profession are simply more aware of
the problem and more willing to report it. This could indeed be
the case, because medical research is a preferred target of research
and training programs in scientific integrity, and because the
severe social and legal consequences of misconduct in medical
research might motivate respondents to report it. However, the
effect of this parameter was not robust to one of the sensitivity
analyses, so it would need to be confirmed by independent studies
before being conclusively accepted.
The lack of statistical significance for the effect of country,
professional position and other sample characteristics is not strong
evidence against their relevance, because the high between-study
variance caused by methodological factors limited the power of the
analysis (the regression had to control for three methodological
factors before testing any other effect). However, it suggests that
such differences need to be explored at the study level, with large
surveys designed specifically to compare groups. A few of the
included studies had done so and found, for example, that
admission rates tend to be higher in males compared to females
[42] and in mid-career compared to early career scientists [19],
and that they tend to differ between disciplines [41,53]. If more
studies attempted to replicate these results, possibly using
standardized methodologies, then a meta-analysis could reveal
important correlates of scientific misconduct.
In conclusion, several surveys asking scientists about misconduct
have been conducted to date, and the differences in their results
are largely due to differences in methods. Only by controlling for
these latter can the effects of country, discipline, and other
demographic characteristics be studied in detail. Therefore, there
appears to be little scope for conducting more small descriptive
surveys, unless they adopted standard methodologies. On the
other hand, there is ample scope for surveys aimed at identifying
sociological factors associated with scientific misconduct. Overall,
admission rates are consistent with the highest estimates of
misconduct obtained using other sources of data, in particular
FDA data audits [11,18]. However, it is likely that, if on average
2% of scientists admit to have falsified research at least once and
up to 34% admit other questionable research practices, the actual
frequencies of misconduct could be higher than this.
Supporting Information
Table S1 Studies excluded from the review.
Found at: doi:10.1371/journal.pone.0005738.s001 (0.14 MB
DOC)
Table S2 Self-report questions included in review, and respons-
es.
Found at: doi:10.1371/journal.pone.0005738.s002 (0.07 MB
DOC)
Table S3 Non-self report questions included in the review, and
responses.
Found at: doi:10.1371/journal.pone.0005738.s003 (0.11 MB
DOC)
Table S4 Sensitivity analysis for meta-regression model.
Found at: doi:10.1371/journal.pone.0005738.s004 (0.07 MB
DOC)
Acknowledgments
I wish to thank Nicholas Steneck, Tom Tregenza, Gavin Stewart, Robin
Williams and two anonymous referees for comments that helped to
improve the manuscript, and Moyra Forrest for helping to search the
literature.
Author Contributions
Conceived and designed the experiments: DF. Performed the experiments:
DF. Analyzed the data: DF. Wrote the paper: DF.
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