I'm a grad students on the academic job market (social sciences, US). Many postings ask for 1-2 writing samples. Is it ever appropriate to send in a paper that has a co-author? I do have other sole-authored products I can send in (book chapter, manuscript under review), but this is the only work that's been published in a well known journal in the field. (I was second author.) Would committees rather see co-authored published work or is there a large premium on sole authored writing samples?
The relative value of co-authored versus solo authored articles varies from field to field, so you should really ask your advisor or some other trusted expert from within your field.
With that said, there is nothing in principle that should rule out submission of coauthored articles as writing samples. Obviously, articles where it is clear that you had a large contribution - e.g. articles where you are first author - are preferred. By submitting such an article in a job application package, you are tacitly implying that you took primary responsibility for the writing of the article (or possibly co-primary responsibility).
Here are some more concrete examples:
- A solo-authored paper. Yes.
- A first-authored paper with your advisor as second author. Yes.
- A first-authored paper with several co-authors on a project of your devising and implementation. Probably.
- A second-authored paper with another graduate student, the authors are in alphabetical order. Maybe, but it's not ideal.
- A conference paper where you are 3rd out of 6 authors. Not appropriate.