表 1. Basic characteristics of the population for the total sample, the group without NSSI behaviors, and the group with NSSI behaviors.

总样本、无NSSI行为和有NSSI行为划分的人群基本特征

Variable	No NSSI (n = 49923)	NSSI (n = 6947)
Age/yr.,	12.81 ± 4.69	12.8 ± 4.72
Sex/case (%)
Male	26479 (53.04)	3087 (44.43)
Female	23444 (46.96)	3860 (55.57)
Education level/case (%)
Elementary school	24110 (89.83)	2729 (10.17)
junior high school	17769 (85.78)	2945 (14.22)
senior high school	8044 (86.34)	1273 (13.66)