What does last authorship mean in various fields? [duplicate]

Question

Author order has been discussed extensively on this site, e.g. here, but these typically focus on the first author. I'm curious as to the meaning of the last author in various fields.

In (theoretical, non high-energy) physics, the last author is typically the one who conceived and directed the project, but may not have done the actual work of performing experiments/simulations/calculations (that would be the first author). The last author usually is someone more senior, but is not necesarily the PI or the most senior author. In fact, one often sees physics papers with a postdoc as the last author and the PI as a middle author. In fields with this convention (which I'll call "last=project leader"), last authorship is as coveted as first authorship, and it is desired for people at the postdoc/early faculty stage of their career to produce last-author papers, as it demonstrates leadership and ability to come up with ideas.

It seems that there are also other conventions. For example, my impression is that there exists a similar but distinct convention: the "last=PI" convention, where the last author is by default the PI, and doesn't come with any connotation of level of intellectual contribution, or the same strong significance attached to the first author position.

As a (possible) example of the difference between these conventions: in physics (or fields with the same convention) a junior person who performed a major leadership role might be "promoted" to last author, while in fields with the "last=PI" convention, they might be promoted to first or co-first author instead.

And (in some fields?) there is the "decreasing-contribution" system, where authors are simply arranged in order of level of contribution and hence the last position would just be the least important one.

So, among fields where author order is non-alphabetical, which follow the "last=project leader" vs "last=PI" vs "decreasing contribution" conventions? Are there possibilities other than these?

Answer 1

In (pure) mathematics it means that the last name of the author comes last when sorted alphabetically.

Answer 2

As a statistician, I have worked in a few fields and, as a statistical reviewer, I've reviewed in more fields. I haven't really got a great answer for field by field, but I've seen:

1a. Alphabetical list of authors

1b. Random order

2a. First author most important, then alphabetical

2b. Same only with random order

3. Last author 2nd most important

4. Last author = PI, or the person who got the grant money, or the most senior

But each of this seems to happen in all the fields I've worked in (psychology, epidemiology, general medicine, neurology, neonatology, social networks, education, …). I'd say there is more variation within field (often by journal) than across fields, but maybe some fields do have a standard --- there are tons of fields I haven't worked in!

Answer 3

In biology is say its both last author=PI AND last author is project leader. Project leader IS the PI, almost always. In fact, PI is short for principal investigator. PIs are usually, but not always, the head of a research group, so the head of the research group is usually the last author. But not always. If a postdoc conceived of, planned, got authorisation and funding for a study. That is, if they were legally responsible for it. If it would be then in the dock if the data were fake, or ethical rules were not followed, then that postdoc would be the PI and the last author. I believe this situation is more common in physics than biology.

The last author is also usually the corresponding author. This is the author most likely to be contactable at the same address and able to answer questions across the total content of the paper in 10 years time.

Answer 4

In chemistry/nanoscience/materials science/applied physics, last author with * is the corresponding author and main-PI. You can have multiple PIs with * for collaborative works, and they appear typically in order of contribution at the end of the author list (the last being the project leader). This goes out the window when people do alphabetical which is less common but still done.

Answer 5

If there is one default convention in condensed matter physics*, it is that the (main) PI is the last author. Many projects may involve multiple PIs, who then tend to collectively be at the end of the author list. In those cases, the precise order can be a matter of politics, or done according to level of involvement. If a postdoc is listed as last author (which seems to happen most often from European research groups?), I would expect them to have had some kind of supervisory role. Last authorships can indeed count more depending on career status, making them more desirable for some authors.

As for who conceived of the project, it is highly variable and cannot be reliably deduced from the author list. For big-budget projects it's most often the PI, but for specific papers it can often be a student or postdoc who had a specific idea for further investigation. Perhaps that is particularly prevalent in theory work. Or it could be that another PI had the idea, but not the expertise**, time or resources to carry out the project. In such cases, depending on the distribution of work, the idea-haver might go anywhere in the author list (or even the acknowledgments). That said, junior people are often motivated to work on their own research ideas so it could well be that the first or second author is the one who was actually driving the project.

---

*Especially mathematical physics work in the condensed matter context sometimes uses alphabetical order, which is ignored here.

**Commonly seen in experiment-theory collaborations, for example.

Answer 6

In medical research, there are guidelines by the International Committee of Medical Journal Editors for what are the responsibilities and meaning of authorship Basically, it agrees with some of the descriptions already in the answers above: The one who contributed the most for the realization of the research presented in the paper goes in front, while the PI or postdoc (little PI ;-) ) is at the end. Usually the last author conceptualized the research developed and presented in the paper.

About the discussion with the corresponding author: This is the person that will answer ANY question regarding the research presented, including files used for images, code for data analysis, ethics grant documentation for animal or human research, etc. I hope this helps you to see the variability in fields.

Answer 7

I am in the social sciences, and from what I have seen - and experienced myself - thus far, the last author of a lab-driven project/paper tends to be the lab P.I.

Answer 8

We use the ordering of authors to denote contribution. The first author did the lion's share of the work and is the communicating author. From there it's declining contribution or specialist contribution (such as preparation of maps... I'm a Geographer). The last author contributed the least relative to the others. By least, I don't mean of little importance. Everyone plays an important role hence they are acknowledged. It is just that these roles and their contribution to the publication are different. In this model there are no freeloaders who are named without contributing. Having discussions at the outset of the writing is critical as this sets the stage for who does what and how people will be acknowledged etc. If roles change, we discuss this openly. Typically, we share responsibilities and hence where people are acknowledged across a series of outputs. I'll lead this one while you do other things... You lead this one while I do other things etc. This model is particularly good when co-publishing with PHD candidates as it provides a framework for them to understand their role and what they have to deliver while socialising them in an open and collegial publishing approach. I hope this helps you 🙂