Is it appropriate to submit a co-authored writing sample to PhD applications? I will be applying to PhD programs in Psychology this fall. Currently, I am in an MA program where we will be assigned to draft a research proposal in the topic of our interest. However, There will be another student co-authoring this assignment with me (we must work in pairs). Is it acceptable or favorable to submit such draft as a writing sample?
If not, what do you suggest might be a good piece to submit?
I suggest that you don't submit a sample that was written jointly. It would defeat the purpose of the request. The reader doesn't know how you write. I suspect that it would be rejected by many (most?) places.
There are a lot of possibilities for what you might submit. An old assignment, perhaps. Or write up something specifically for this purpose. Perhaps you could write a proposal for some specific research that interests you, showing that you have done some background reading and are looking ahead.