Hah, glad you asked. It's very simple. Thread. 1/n
First you subdivide all authors into two groups, people who have PI status (usually some sort of faculty member) and people who don't (grad students, postdocs, technicians, etc.). 2/n
Among the non-PIs, you sort them in order of their contribution, from most to least. 3/n
If multiple non-PIs have done so much that they all deserve first-author status, you mark them with a *equal contribution, but you still list them in order of their relative contribution. 4/n
In other words, if three non-PI authors made equal contributions to a paper, they are listed in positions 1, 2, and 3, marked with *equal contribution, but _in relative order of their contribution_ (obviously). 5/n
Now the PI authors. Those you sort in reverse order of the relative contribution of their affiliated non-PI authors. 6/n
In other words, the PI supervising the non-PI in first position goes last, the PI supervising the non-PI in second position goes second-to-last, etc. 7/n
If different PIs supervised different numbers of non-PI authors, you may have to sum their relative contributions to figure out where the PIs rank, but here it gets sketchy and possibly controversial. Hopefully you have good conflict resolution skills. 8/n
If multiple PIs have made equal contributions, you can also mark them with *equal contribution. You still use the reverse ranking to determine their actual order. 9/n
For papers with many different authors, you may genuinely have a bunch of authors where you realistically can't rank their relative contributions. They made some contribution, sufficient to warrant co-authorship, but clearly not enough to be near the first or last position. 10/n
Those you can sort alphabetically and stick in the middle. 11/n
So, you end up with three blocks of authors, in this order:
1. non-PI major contributors, ranked in descending order of contribution
2. minor contributors, ranked alphabetically
3. PI major contributors, ranked in ascending order of importance
12/n
1. non-PI major contributors, ranked in descending order of contribution
2. minor contributors, ranked alphabetically
3. PI major contributors, ranked in ascending order of importance
12/n
Exceptions can be made in special cases, e.g. for review papers PIs may be listed at the beginning. 13/n
The end. 14/14
