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?