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Table 1 Descriptive statistics for control and independent model variables

From: Parental smoke exposure and the development of nicotine craving in adolescent novice smokers: the roles of DRD2, DRD4, and OPRM1 genotypes

Variable Response categories Mean (SD) Response frequencies Skewness (SD)
Sex Male   53.3 % .13
Female   46.7 % (.12)
Education University preparatory   8.9 % -.19
Senior general   22.0 % (.12)
Junior general   34.2 %
Preparatory vocational   34.8 %
Ethnicity Not Dutch   4 % -.47
Dutch   96 % (.12)
Age of smoking initiation   11.67 (1.90)   
Baseline smoking <1 per day   83.7 % 2.70
1-5 per day   9.6 % (.21)
6-10 per day   5.2 %
>10 per day   1.4 %
DRD2 Taq1A A2A2   64.2 % .59
A2A1/A1A1   35.8 % (.12)
DRD4 48 bp <7-repeat   64.2 % .60
VNTR ≥7-repeat   35.8 % (.12)
OPRM1 A118G AA   78.7 % 1.41
AG/GG   21.3 % (.12)
Parental smoke exposure No smoking parents   54.0 % 1.00
Smoking parent(s)/no exposure   10.2 % (.13)
One smoking parent/exposed   22.5 %
Two smoking parents/exposed by one   2.3 %
Two smoking parents/exposed by both   11.0 %