Data processing and statistical analysis
HT
The postures and muscle activities were summarized as the 10th, 50th, and 90th percentiles of all data within each task, with each pair of loupes for each participant. For the angular velocities, only the 50th percentile was used (Equal ranks in the final survey were normalized so that the sum of all ranks remained at 6, e.g., a rank of [1, 1, 2] would be normalized to [1.5, 1.5, 3]. The number of surgical errors was calculated as the average value of the two examiners.All quantitative measures of each task were compared separately across three types of loupes (own, LT, and HT), and they were matched on the individual level. The normality and sphericity of the dataset of each measure were checked by the Shapiro–Wilk test and Mauchly’s test. Since the normality and the sphericity of most measures did not fulfill the criteria, the Friedman test was used to test the overall significance of the differences in each measure of each task between the three pairs of loupes (own, LT, and HT). 