Mazzolini, Margaret, and Sarah Maddison. "When to jump in: The role of the instructor in online discussion forums." Computers & education 49.2 (2007): 193-213.

This study examines the impact of instructor participation in asynchronous discussion forums on student participation and perception. It analyzes over 40,000 postings from nearly 400 forums and over 500 university evaluation surveys across six semesters. The study investigates how instructor participation rates, timing of posts, and nature of postings (questions, answers, or a mix) influence student behavior. Results indicate that instructors' posting behaviors can affect student discussions in unexpected ways and that instructors' perceptions of their online teaching often differ from observed data. Additionally, common metrics like student participation rate and thread length may not accurately reflect forum health or learning quality.