The author identified and measured 5 landmarks of mandibula two times according to ten digital cephalometric radiographs selected randomly, then the mean error of measurements were determined.

• 随机选择10张数字化头颅侧位定位片,由作者对下颌骨上的5个测量指标进行先后两次定点和测量,然后对两次测量结果进行比较,检验重复测量误差的大小,是否对测量结果有影响。