How do researchers decide whose name comes first on a paper?

Question

Is it based on who contributed the most? How is this determined? Is it alphabetical? If so then someone with an A last name can contribute barely anything and everyone will still call it “Alberts et. al”

In: Other

Answer 1

My PI recently said it’s

1. The person who contributed the most to the project, ie it was *their* project
2. next most important contributor, eg lab-mate or direct collaborator who worked on it
3. collaborators who didn’t work directly on it but supervised/advised decisions
4. reviewers
5. the lab PI