Statistical analysis
Statistical analysis and sample size calculation were performed using the JMP 11.2.0 software (SAS Institute, Cary, NC, USA). First, the overall, efficiency, and penalty scores of all drills in cycles 1–10 were compared between the video and control groups. Subsequently, the overall, efficiency, and penalty scores in each cycle as well as each drill were analyzed and compared between both groups. Moreover, the detailed penalty scores for each drill were compared between the groups. Finally, a CUSUM analysis was performed to compare the learning curves between the groups. The cumulative sums of the differences in each drill from the total “time to completion” were calculated based on the cycle. A pooled mean CUSUM was plotted to summarize the results [