Experimental Design Details
The intention-to-treat analysis was adopted in this study. The experiment started on September 1, 2020 and ended on December 23, 2020. The intervention started from the 4th week of the semester, i.e., on September 21, 2020. The sample consisted of 725 students from 7 statistics courses offered by the University of Hong Kong in the first semester of 2020-2021, among which 560 and 165 are undergraduate and postgraduate students, respectively. For the two large courses with enrollment over 140 (i.e., STAT1600 and STAT1603), students were randomly assigned to either the hybrid (i.e., intervention) or online (i.e., control) teaching mode in ratios of 1:2 and 1:3, respectively, whereas students in other courses were randomly assigned to the two modes in a ratio of 1:1. That is, a stratified randomization was adopted for this study with course code as the stratification variable. The difference in the assignment ratio was to comply with the COVID-19 measure that the number of students in a classroom could not exceed one third of its maximum capacity.
Lecture and tutorial materials were posted on the e-learning platform Moodle, which were accessible to both hybrid and online mode students. In each week, 2-3 hours of lectures and 1 hour of tutorial were conducted, during which the hybrid mode students received face-to-face instructions, whereas the online mode students received identical instructions via the online meeting platform Zoom simultaneously. Hence, the only difference between the hybrid and online teaching modes is that, the hybrid mode students received face-to-face lectures and tutorials, whereas the online mode students received exactly the same live-streamed lectures and tutorials on Zoom. Both groups had access to the recorded teaching videos.
The first two weeks of the semester were the add/drop period during which students in the seven courses were informed to participate in the study and their informed consents were collected. In the third week of the semester, an online pretest was given to all students in the experiment, and it served as a baseline variable indicating students’ ability and understanding of course prerequisite knowledge. Owing to the COVID-19 pandemic, students were allowed to choose between the Pass/Fail and Letter grading options for each course taken, and would receive only a Pass/Fail grade on the transcript for the course if the Letter grading option was opted out. There were two class tests (excluding the pretest) and 3-5 take-home assignments, and an online final exam for each course. The five outcome variables (i.e., the final weighted, final exam, coursework, test and assignment scores) along with other baseline variables such as gender, grading option, pretest score, course code, course level (undergraduate vs postgraduate) and technicality (technical vs non-technical) were collected for the purpose of this study. Note that the final exam score was still collected even if a student opted for the Pass/Fail grading option.