The situation:

Two PhD students named 'Theory' and 'Experiment' are working on a project. Both are experimentalists by training but, from experiences working on a separate project, Theory comes up with an idea for a new experiment. Positive results from this experiment would have a small but significant impact on their field. However, Theory does not have expertise on the particular instrument required to conduct the experiment so, with the blessing of their adviser, Theory enlists Experiment who is an expert at using the instrument. Theory guides the experiment but the execution is all done by Experiment.

Happily, the results are positive!

The question is, given that Theory and Experiment agree to share first authorship, who should be listed first?

Edit: after writing this I found this thread Had the idea vs. did the work: Who should be the lead author? which is very similar to this question.

There's also an interesting discussion of the issue in this blog: https://funkdoctorx.wordpress.com/2012/02/27/co-first-author-and-cvs/

  • 84
    As someone working in a field where authors are listed alphabetically, I feel this "first author" thing is getting out of hand. We decided that first authors are more important; then shared first authorship was invented. Now people start suggesting that, among shared first authors, the first one listed is more important. What comes next, shared first first authors? Commented Jul 19, 2017 at 18:43
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    If the order of shared-first authors matters, you're not really shared-first authors.
    – JeffE
    Commented Jul 19, 2017 at 20:03
  • 7
    Money guy, for sure.
    – RoboKaren
    Commented Jul 20, 2017 at 0:00
  • 26
    @FedericoPoloni All first authors are first, but some first authors are more first than others. - Orwell, G. et al
    – Deepak
    Commented Jul 20, 2017 at 0:51
  • 5
    Possible duplicate of Why do people sometimes put authors with equal contribution in non-alphabetical order?
    – Wrzlprmft
    Commented Jul 20, 2017 at 7:43

5 Answers 5


Shared first authors are listed alphabethically, at least that's what makes sense, otherwise they are not shared first authors!! I'd go with that no doubt.

From your comments I would say that your are the Experiment person, as you seem to be diminishing the role of the Theory person (he/she simply did so and so...).

From your description, the Theory person came up with the idea and guided the experiments, while the Experiment person simply run the experiments. As a general principle, I would tend to side with the Theory person (Peter's answer here seems to corroborate my view). I believe it also matters who is going to write most of the paper, which you do not mention.

However, as we are all a bunch of strangers on the internet, there's no actual way of knowing which is the case (the idea may be too simple or the experiment may be very complex, and so on...). The best thing to do would be to talk to your supervisor.

Most importantly, don't cling on unimportant details, as you already have a shared first-author status. Move on. This is the kind of meaningless thing that can ruin a scientific collaboration for good.

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    At least in my field, shared first (co-first) are not listed alphabetically, and additional (but small) weight is given to internal ordering of first authors. I agree it is silly, but the whole ordering method is distorted (in some papers I saw 4 co-first authors).
    – Bitwise
    Commented Jul 20, 2017 at 6:22
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    From the information we have I'd find it hard to lean either side. From the description given, I could also conclude that the Theory person might have had a vague idea, like "wouldn't it make sense to apply that method to that data pool I just discovered?!" and then the Experiment person went and actually did the work. Such an idea might be common enough that a lot of people have it, but don't spend the work to actually cary out any experiments. It might also be that Theory came up with a lot of theoretical frameworks explaining why the experiments could be a good idea, we don't know. Commented Jul 20, 2017 at 15:02
  • In the end it really depends on how much efforts both authors spent (and how valuable their efforts are to the project), and they seem to agree that it's about the same. Commented Jul 20, 2017 at 15:03

Throw a dice to decide who comes first. Then write a follow-up paper and inverse the order. Sometimes there is no right and wrong all you can aim for is fairness in the long run.


I'd think carefully about how much work has been invested by each student and scientific contribution, and how much each student will guide the writing of the paper. Based on what you've said so far I'd tend toward listing Experiment first. If Theory devoted more effort than I thought, perhaps co-first.

Did Theory say, "It's worth testing X, because if this is true, then Y"? Or did the student develop a quantitative mathematical model that is motivating the paper? Who is making the decisions about experimental details? Is Experiment making all of the decisions, because he/she knows the system being studied? Or is Theory making all of the scientific calls, and Experiment serving as a technician who happens to be expert in a particular tool?

I would have a difficult time arguing, however, that the student who performed all of the experiments - and without whose experience the project wouldn't have worked - could be listed less than co-first, though.

Edited to add: in case anyone's wondering, I'm a theorist.

  • #AJK thanks for your insight. I agree with your last paragraph. FYI Theory simply realized that an extant quantitative mathematical model predicted something never before tested. So yes, Theory said "It's worth testing X, because if that is true, then Y". The decisions about the experiment are being made equally. Theory knows how the instrument works and has used other commercial versions of the instrument but the version Experiment is using is more specialized and much more delicate so the adviser decided to have only Experiment become proficient on it.
    – ZacHammer
    Commented Jul 19, 2017 at 19:16
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    It's hard to compare ideas with work. Did the idea contribute more to the paper than the actual work done? It's hard to say in a lot of cases.
    – user64845
    Commented Jul 19, 2017 at 21:55
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    So Theory has an idea, and he wants to enlist somebody to run the experiments. He could chose Experiment, or he could probably chose many other people. No matter who he chooses, he gets a paper from it; but because he decided to chose Experiment, this somehow makes Experiment more important and essential but Theory less important for the paper.
    – Nick S
    Commented Jul 20, 2017 at 2:29
  • @DVSA - I agree entirely, which is why I suggested asking that set of questions.
    – AJK
    Commented Jul 20, 2017 at 2:43
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    @Nick: But maybe no one else has the same idea as Theory and thus, he can find any other minion to do his bidding to bring this knowledge to the rest of us, while Experiment may never give the world this knowledge on his own. Point being, it's hardly clear in such cases and as much as both brought about the same sweat in different forms to the project, I'd see them as equal contributors. Since they already share first author, I'd really be pragmatic with the remaining order. Commented Jul 20, 2017 at 11:39

My guess is the poster is Theory. Theory believes it's their original idea and feels the credit belongs to them but is worried that asking Experiment to be second author might be offensive.

In my field, usually the person who proposes and "owns" the project is the first author. However, usually the political setup is that both make clear that we do more than one paper out of this and that Theory is first author for the first paper and Experiment can be first author for a second follow up paper, especially if the second paper is an "experimental" or "methodological" extension of the first paper.


The answer heavily depends on your major and type of research. For example, most of the time in applied chemistry developing an experimental setup and conducting experiment for a very simple idea require a lot of efforts and expertise while in other cases (most of the time in theoretical computer science) coming up with new idea require a rigorous theoretical (analytical and mathematical) analysis which is much more challenging compare to required experiments to prove the idea.

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