How common is scientific misconduct? To answer this long-standing and crucial question, different approaches have been employed, and they have produced a corresponding variety of estimates. In U.S. government investigations, scientific fraud is documented in about 1 every 100,000 researchers or 1 every 10,000 according to a different counting. Paper retractions from the PubMed library due to misconduct have a frequency of 0.02 %, which led to speculations that between 0.02 and 0.2 % of papers in the literature are fraudulent.
Eight out of 800 papers submitted to The Journal of Cell Biology had digital images that had been improperly manipulated, suggesting a 1 % frequency. Finally, routine data audits conducted by the U.S. 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.
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 below), and are very hard to detect in the data. 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 willfully distorted their data. Many surveys have asked scientists directly about their behavior, but they have used different methods and asked different questions, so their results have been deemed inconclusive and/or difficult to compare.
Fanelli D (2010) What surveys tell us about scientific frauds. BIOforum 14:16-17