Q: What does the second "out for review" status mean?
I submitted 2 papers at a time to a journal of IOS Press. The status of both papers became “out for review” after a while from submission, and about 3 months later, the status was again updated with “out for review” for both papers. What does this mean? I sent an inquiry to the journal, but no response was received so far.
The "out for review" or "under review" status indicates that your paper has passed the initial admin check and is now being scrutinized by peer reviewers. The fact that your paper has been considered for and sent for peer review is a good sign!
Although you have stated that your paper's status was initially "out for review" and then was updated with the same status about three months later, you haven't shared which status appeared between this time period. Based on my understanding, once the peer review process is complete, the status of the manuscript changes to "ready for decision" or a similar variation of this. This change in status indicates that the reviewers have sent your paper back to the editor with their comments and it is now up to the editor to make a decision about your paper.
Post this, if your paper's status changes back to “under review,” then it is likely that the editor is probably not satisfied with the reviews and has therefore sent your manuscript for an additional review. This could also happen if the reviewers have conflicting views or if one or more of the reviews are weak or unsatisfactory. However, I don't think that you should be worried about this, as it is quite common and does not indicate anything about the outcome of your paper.
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This content belongs to the Journal submission & peer review Stage