A published article can be retracted in the following situations-
1. There is clear evidence that the findings are unreliable, either because of misconduct (e.g. data fabrication) or honest error (e.g. miscalculation or experimental error).
2. The findings have previously been published elsewhere without proper cross referencing, permission or justification (i.e. cases of redundant publication).
3. If it constitutes plagiarism.
4. If it reports unethical research.
An expression of concern is issued in the following situations-
1. Inconclusive evidence of research or publication misconduct by the authors.
2. There is evidence that the findings are unreliable but the authors’ institution will not investigate the case.
3. They believe that an investigation into alleged misconduct related to the publication either has not been, or would not be, fair and impartial or conclusive.
4. An investigation is underway but a judgement will not be available for a considerable time.
A correction is issued in the following situations-
1. Small portion of an otherwise reliable publication proves to be misleading (especially because of honest error).
2. Author/contributor list is incorrect (i.e. a deserving author has been omitted or somebody who does not meet authorship criteria has been included).
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