Fig. 6.

Box and whisker plots of scores for social life function 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 subjects in their 20–60 s and those in their 80 s (Steel–Dwass test; *p < 0.05) in both genders. Moreover, a significant difference in the scores between female subjects in their 30 and 70 s was observed (Steel–Dwass test; *p < 0.05). The scores had a tendency to decrease with age in both genders (Jonckheere–Terpstra test; p < 0.001)