All persons designated as authors must qualify for authorship, and all those who qualify must be listed. Acquisition of funding, the collection of data, or general supervision of the research group, by themselves, do not justify authorship. As well as being accountable for the parts of the work he or she has done, an author should be able to identify which co-authors are responsible for specific other parts of the work. In addition, authors should have confidence in the integrity of the contributions of their co-authors. Authorship credit should only be based on:
Substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work
Drafting the work or revising it critically for important intellectual content
Final approval of the version to be published
Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved
All of these conditions must be met to qualify for authorship. When an individual has made a contribution to the manuscript but does not meet these criteria, their contribution should be recognised in the acknowledgements. Written permission to be acknowledged should have been obtained from such individuals, since readers may infer their endorsement of the data and conclusions.