1. In general:
2. If guaranteed CO-authorship
1. The gold standard of systematic reviews, the Cochrane Group, recommends librarians serve as co-authors so that SRs are based on comprehensive searching and the resulting findings are therefore as objective as possible, being based on the widest possible collection of studies. The type of searching required for systematic reviews is deeper than usual and librarians are more familiar with sources on UNpublished studies that will prevent reviewers from suspecting publication bias in the final project.
2. The International Committee of Medical Journal Editors recommends authorship credit based on these 4 criteria*:
Librarians meet the 1st criterion when they help you shape your research question and certainly in “the acquisition….of data for the work”
If they have performed the searches upon which the review is based, they meet the 2nd criterion in writing the segment of the Methods section in which they describe terms and combining strategies they used in searching for the literature and in supplying the numbers for or drafting the PRISMA diagram.
Again, if they have performed the searches upon which the review is based, they should be involved in drafting, editing and final approval of the version of the study to be published, the 3rd criterion for authorship.
If they have performed the search and not been involved in writing the Methods section or approving the final version, no other author should feel comfortable agreeing to be accountable for ALL aspects of the work without the librarian’s agreement to also be accountable as an author, the 4th criterion for authorship.
*International Committee of Medical Journal Editors – Defining the Role of Authors and Contributors- Who is an Author? http://www.icmje.org/recommendations/browse/roles-and-responsibilities/defining-the-role-of-authors-and-contributors.html#two