We apply a novel mistake index to assess trends in the proportion of corrections published between 1993 and 2014 in Nature, Science and PNAS. The index revealed a progressive increase in the proportion of corrections published in these three high-quality journals.
The index appears to be independent of the journal impact factor or the number of items published, as suggested by a comparative analyses among 16 top scientific journals of different impact factors and disciplines. A more detailed analysis suggests that the trend in the time-to-correction increased significantly over time and also differed among journals (Nature 233 days; Science 136 days; PNAS 232 days).
A detailed review of 1,428 errors showed that 60% of corrections were related to figures, authors, references or results. According to the three categories established, 34.7% of the corrections were considered mild, 47.7% moderate and 17.6% severe, also differing among journals. Errors occurring during the printing process were responsible for 5% of corrections in Nature, 3% in Science and 18% in PNAS.
The measurement of the temporal trends in the quality of scientific manuscripts can assist editors and reviewers in identifying the most common mistakes, increasing the rigor of peer-review and improving the quality of published scientific manuscripts.