Figure 6.

Box-and-whisker plots of the absolute errors in position and direction. (a) Position errors of the entry points. (b) Direction errors of the guide holes. The central mark indicates the median, and the bottom and top edges of the box indicate the 25th and 75th percentiles, respectively. The whiskers extend to the most extreme data points not considered outliers (approximately ± 2.7σ and 99.3% coverage for a normally distributed dataset), while outliers are plotted individually using the ‘+’ symbol.