How common is scientific misconduct? It's a tough question to answer. Scandals like Hwang Woo-Suk's faked stem-cell lines or Jon Sudbø's made-up cancer trials have demonstrated that fraudulent research is easy to publish, even in the most prestigious print journals, but are they deviations of a few "bad apples" or evidence that a great deal more is never discovered? The actual numbers are a matter of dispute.
In a PLoS ONE meta-analysis of surveys questioning scientists about their misbehaviors, Daniele Fanelli of the University of Edinburgh, a PhD in the behavior and genetics of Malaysian and Panamanian tropical wasps, suggests that altering or making up data is more frequent than previously estimated and might be particularly high in medical research.
How to know? Estimates based on indirect data, such as official retractions of scientific papers or random data audits, have produced inconsistent results. Researchers have also asked scientists directly, with surveys conducted in different countries and disciplines, but they have used different methods and asked different questions, so their results were also inconclusive.
To try and make those surveys comparable, Fanelli focused on behaviors that actually distort scientific knowledge (excluding data on plagiarism and other kinds of malpractice) and extracted the frequency of scientists who (a) recalled having committed a particular behavior at least once or (b) who knew a colleague who did.
On average, across the surveys, around 2% of scientists admitted they had "fabricated" (made up), "falsified" or "altered" data to "improve the outcome" at least once, and up to 34% admitted to other questionable research practices including "failing to present data that contradict one's own previous research" and "dropping observations or data points from analyses based on a gut feeling that they were inaccurate."
In surveys that asked about the behavior of colleagues, 14% knew someone who had fabricated, falsified or altered data and up to 72% knew someone who had committed other questionable research practices.
In both kinds of surveys, misconduct was reported most frequently by medical and pharmacological researchers. This suggests that either the latter are more open and honest in their answers or that frauds and bias are more frequent in their fields. If you choose the latter interpretation, it may be due to fears that only government sponsored scientists have a motivation to be ethical and industry is distorting scientific evidence to promote commercial treatments and drugs.
A meta analysis of how honestly scientists think scientists in other disciplines or in the private sector behave in regard to ethical conduct would be interesting.
As in all surveys asking sensitive subjective questions - or ones implicating the behavior of other people - it is likely that some respondents did not reply honestly, especially when asked about their own behavior. Therefore, a frequency of 2% may be a conservative estimate while it remains unclear how the figure of 14% should be interpreted.
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