Shaw, M. et al. (2013) An Evaluation of Student Outcomes by Course Duration in Online Higher Education Online Journal of Distance Learning Administration, Vol. 16, No. 4
This study looked at the effect of designing a course that would otherwise last 16 weeks into eight weeks. The conclusion – no significant difference in student scores, so, yes, students can do just as well on compressed online courses:
Both 8 and 16 week course options provided similar learning experiences for students in terms of content given, scores earned, and total assignments completed. What is not at all evident from the literature is whether generalizability is possible. In some situations, traditional-length terms might yield better assessment results than shorter-length courses. If research informs practice, though, enough data exist to support compressed courses. Yet, before administrators and educational theorists view this as a carte blanche for shorter-term courses, it is vital to understand clearly the objectives of learners and of school administrators.
For a whole series of papers on the effect of the time factor in online learning, see the eLearn Centre’s publications at the Open University of Catalonia