Table 1 Sample Characteristics for Each Group.

From: Psychopathology profiles and longitudinal correlates of nonsuicidal self-injury in youth: a machine-learning approach

 

Comparison (n = 1101)

Group 1 (n = 117)

Group 2 (n = 127)

P- valuea,b

Effect Sizes

     

Group 1 vs. Comparison

Group 2 vs. Comparison

Group 2 vs. Group 1

Site (São Paulo), n (%)

546 (50%)

55 (47%)

78 (61%)

0.021

h = − 0.05

h = 0.24

h = 0.29

High-risk Cohort Strata, n (%)

660 (60%)

90 (77%)

77 (61%)

0.002

h = 0.37

h = 0.01

h = − 0.35

Sex Assigned at Birth (Female), n (%)

494 (45%)

70 (60%)

50 (39%)

0.003

h = 0.30

h = − 0.11

h = − 0.41

Age, M (SD)

       

Baseline

10.14 (1.89)

9.99 (1.89)

9.63 (1.81)

0.015

d = − 0.08

d = − 0.27

d = − 0.19

First follow-up

13.45 (1.91)

13.32 (1.90)

12.92 (1.81)

0.011

d = − 0.07

d = − 0.28

d = − 0.21

Second follow-up

18.12 (1.97)

17.97 (1.94)

17.59 (1.84)

0.015

d = − 0.08

d = − 0.27

d = − 0.20

Ethnicity, n (%)

       

White

605 (55%)

65 (56%)

75 (59%)

0.457

V = 0.04

V = 0.04

V = 0.12

Black

139 (13%)

19 (16%)

11 (8.7%)

Mixed

353 (32%)

33 (28%)

41 (32%)

Indigenous

1 ( < 0.1%)

0

0

–

–

–

–

Asian

3 (0.3%)

0

0

–

–

–

–

SES Score, M (SD), and Strata, n (%)

       

Baseline

18.52 (4.57)

17.73 (3.99)

19.08 (4.49)

0.054

d = − 0.18

d = 0.12

d = 0.32

Low (D/E)

115 (10%)

15 (13%)

9 (7.1%)

    

Intermediate (C)

789 (72%)

84 (72%)

92 (72%)

High (A/B)

197 (18%)

18 (15%)

26 (20%)

First follow-up

18.54 (4.43)

18.56 (3.81)

18.57 (4.39)

0.865

d < 0.01

d = 0.01

d < 0.01

Low (D/E)

114 (10%)

8 (6.8%)

5 (3.9%)

    

Intermediate (C)

794 (72%)

92 (79%)

100 (79%)

High (A/B)

193 (18%)

17 (15%)

22 (17%)

Second follow-up

24.30 (7.41)

22.85 (6.24)

25.02 (8.60)

0.222

d = − 0.20

d = 0.10

d = 0.29

Low (D/E)

142 (13%)

21 (18%)

17 (13%)

    

Intermediate (C)

699 (63%)

74 (63%)

78 (61%)

High (A/B)

260 (24%)

22 (19%)

32 (25%)

Mother Educational Level, n (%)

   

0.371

V = 0.04

V = 0.04

V = 0.13

Primary or less

403 (37%)

40 (34%)

48 (38%)

    

Secondary

584 (53%)

69 (59%)

62 (49%)

    

Tertiary (any level)

103 (9.4%)

7 (6.0%)

16 (13%)

    

Missing, n (%)

11 (1.0%)

1 (0.9%)

1 (0.8%)

    

IQ, M (SD)

102.19 (16.90)

104.22 (18.34)

104.60 (15.04)

0.275

d = 0.12

d = 0.14

d = 0.02

Missing, n (%)

94 (8.5%)

9 (7.7%)

15 (11.8%)

    
  1. SES socioeconomic status, IQ intelligence quotient.
  2. Groups: Group 1 = High Psychopathology; Group 2 = Low Psychopathology. Mother’s Education Level (3-category recode of the 8-level scale): Primary or less — levels 1–3 (No schooling; Primary incomplete; Primary complete); Secondary — levels 4–5 (High school incomplete; High school complete); Tertiary — any higher education — levels 6–8 (Higher education incomplete; Higher education complete; Postgraduate). Statistical analyses.
  3. aFisher’s exact test for categorical variables (Site, High-risk Strata, Sex, Ethnicity, Mother’s Education Level).
  4. bKruskal–Wallis rank-sum test for continuous variables (Age, SES Score, IQ). Effect sizes: Cohen’s d (continuous), Cohen’s h (binary), and Cramér’s V (categorical).
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