When mistakes in a published study are picked up they need to be reported so that past, present and future readers of the paper do not base their ongoing research on false premises.
Sometimes, deciding between retracting an article and publishing a correction can be difficult. It is possible that an error can affect large parts, but not all of a paper. What is in the best interest of the research community: to retract the whole paper so that it is essentially struck from the scientific record? Or to publish an Erratum to clarify which of the conclusions can be considered sound and which should be disregarded?
This was the choice faced by Genome Biology when the author of a paper published in the journal reported an error that affected the results of several sections of his paper. Steve Horvath, from the University of California Los Angeles, contacted the journal very soon after the publication of his paper ‘DNA methylation age of human tissues and cell types‘.
To his immense dismay he realized that he had made a software coding error that affected the results reported in a large part of his paper. It is to his great credit that he contacted the journal as soon as he realised this error. Quickly, an online comment to this effect was posted to make readers aware, although of course such commenting does not replace a formal Erratum or Retraction.
It is worthwhile clarifying what the options are when such an error is reported. After Horvath’s comment was posted, the journal was contacted by several community-minded researchers asking us to either retract the article or replace it with a corrected version.
Journals cannot simply correct a published article. That is considered, rightly, to be ‘rewriting history’.
Journals cannot simply correct a published article. That is considered, rightly, to be ‘rewriting history’ and the accepted guidelines in scientific publishing (as recommended by COPE, the Committee on Publication Ethics) are that a formal correction notice must be published, which is permanently associated with the paper, both on the journal’s website and in databases such as PubMed.
The sound thinking behind this is that it’s important to see the full history of a published paper – readers must be able to view the flawed version that was originally published, along with a clear description of where errors lie. This is essential so that those who have already read the paper in its original form know exactly which of the original results and conclusions have changed. That would not be possible if the original version was simply replaced by a new, correct one.
So should we have retracted the paper? The effects of the error that Horvath reports are limited to the sections of his paper that look at cancer tissues. The preceding sections that deal with non-cancer tissues are unaffected, and indeed this is the bulk of the paper.
Although there have been some requests to retract the paper, we decided not to do this. We felt it of greater benefit to the research community to let the unaffected results and conclusions remain as part of the scientific literature so that this work can be built on. We have now published a detailed Erratum, which has been peer reviewed, in which Horvath explains the error and how it affected the results he originally reported.
One aspect of this process that we – Genome Biology – regret is the length of time it has taken to publish the Erratum. The paper was published in October 2013 and Horvath’s comment was posted in early November 2013. It is now May 2015.
Publishing a complicated Erratum such as this one is never a fast process as it involves back-and-forth between authors, editors and reviewers. However, the time taken to publish this Erratum has been unduly long and we sincerely apologize for this delay. Procedures are now in place so that the process will be much faster in future for any papers published in Genome Biology that require correction.