Does the manuscript report on primary research?
PLoS ONE is designed specifically as a medium for primary, scientific research. As such, it is not suitable for the publication of reviews, mini-reviews, opinion pieces, hypothesis papers, commentaries, essays or other items of secondary literature. Commissioned reviews, synthesis and commentary articles are considered but only where they form part of an agreed collection. The number, format and prospective authors of these articles are defined by the PLoS ONE staff and the collection organizers prior to their submission. Systematic reviews are considered for publication in PLoS ONE but are limited to areas where appropriate standards for conduct and reporting apply and where the methods ensure the utmost rigor in the comprehensive and unbiased sampling of existing literature. A systematic review differs substantially from a narrative-based review or synthesis article and has its roots in the medical sciences (but is beginning to be applied to other disciplines such as environmental sc