Fig. 4.

Box and whisker plots of scores for lumbar spine dysfunction in the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire by gender and age group. The lines on the box correspond to the quartiles. Whiskers indicate the furthest point within 1.5× interquartile range from the box. Significant differences were observed in the scores between the younger generation in their 20 and 30 s and subjects in their 70 s, and between subjects in their 20–60 s and those in their 80 s in both genders (Steel–Dwass test; *p < 0.05). The scores had a tendency to decrease with age in both genders (Jonckheere–Terpstra test; p < 0.001)