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Table 2 Means and standard deviations, and differences between groups on study variables

From: Evaluating the effectiveness of the SMART contract-signing strategy in reducing the growth of Swedish Adolescents’ substance use and problem behaviors

  Long-term participants Short-term participants SPON-participants  
  (n = 112) (n = 200) (n = 102)  
  M SD M SD M SD F-test p
Baseline demographic and SES variables        
 Sex 1.59x .49 1.51x .50 1.33z .47 7.14 (2,357) .001
 One non-Nordic parent .82 .38 .88 .33 .77 .42 2.37 (2,352) .095
 Monthly allowance .19 .23 .24 .26 .18 .24 1.69 (2,353) .186
 Books at home .70x .24 .62y .23 .52z .26 13.10 (2,354) .001
 Type of residence 1.06 .24 1.07 .26 1.08 .28 .194 (2,357) .824
Smoking         
 T1 .12 .78 .19 .60 .19 .53 .35 (2,354) .704
 T2 .16 .79 .36 .94 .47 .99 2.94 (2,380) .054
 T3 .28x .71 .84x 1.47 1.12z 1.71 10.64 (2,411) .001
Snus use         
 T1 .07 .60 .06 .42 .08 .31 .04 (2,357) .961
 T2 .07 .62 .13 .58 .26 .79 2,00 (2,379) .137
 T3 .16x .55 .59x 1.41 .73z 1.33 6.75 (2,408) .001
Alcohol use         
 T1 1.47 .69 1.64 .77 1.73 .86 2.96 (2,353) .053
 T2 1.57x .77 1.98x 1.01 1.91z 1.00 6.56 (2,379) .002
 T3 2.04x 1.06 2.57x 1.21 2.59z 1.13 8.65 (2,410) .001
Drunkenness         
 T1 1.34x .78 1.48xz .61 1.60z .82 3.06 (2,353) .048
 T2 1.44 .88 1.60 .90 1.67 1.06 1.64 (2,381) .195
 T3 1.72x 1.03 2.43x 1.60 2.41z 1.53 9.52 (2,408) .001
Delinquency         
 T1 2.14 .86 2.25 .83 2.40 1.11 1.87 (2,352) .156
 T2 2.24 1.00 2.37 1.11 2.47 .86 1.22 (2,380) .295
 T3 2.23x .72 2.52xz 1.33 2.76z 1.62 4.59 (2,410) .011
Bullying         
 T1 1.1 .58 1.08 .32 .108 .31 .14 (2,356) .868
 T2 1.05 .23 1.14 .49 1.16 .45 1.80 (2,379) .167
 T3 1.06 .41 1.11 .46 1.16 .48 1.17 (2,409) .313
  1. Groups with different superscript letters did differ (p < 0.05) on measured outcomes (ANOVA, Tukey’s HSD), and groups with similar superscripts did not significantly differ