I don't know. No research necessary. I really think a person learns how to teach writing by writing, by grading essays one paragraph at a time, one sentence at a time, and finally one word at a time. By having conferences, working in groups, working as a lecturer, by reading and imitating and creating and criticizing. In short, by practice.
Good teachers practice teaching.
Bad teachers practice something else, often b.s. Check this box if you would like this submission to be considered for publication as a letter to the editor in the printed Chronicle. Be sure to include your name and affiliation. Legitimate requests for anonymity will be honored. Submissions may be condensed or edited for clarity.