Multiple Substance Use Among Adolescents in Scotland: Profile and Trends

This report examines the prevalence of regular use of 2 or more substances among adolescents in Scotland, and key factors associated with multiple substance use.


Appendix C: Regression

Interpreting Logistic Regression models

Table C.1 shows a selection of the output from the logistic regression model of whether any substance use. The first two columns indicate the different predictor factors included in the model. All variables have been treated as categorical variables.

The column headed 'Sig.', shows whether the factor is significant. A value of less than 0.05 in this column suggests that this factor is significant. In Table C.1, the figure for female (vs. male) is less than 0.05, it follows that - after controlling for the effect of all other factors in the model - the likelihood among females using at least one of the three types of substance is different from the likelihood among males.

The column headed 'Beta' indicates the direction of the effect. A positive value indicates that those in the category are more likely to use at least one substance, and vice versa. For example, females are less likely than males to take at least one substance as the co-efficient is negative.

Logistic regression models compare different categories against a reference category. In Table C.1, large urban area has been set as the reference category for the urban/rural classification, and the other categories are a series of comparisons with this category.

The column headed "Exp(B)" gives the odds ratio. This indicates the size of the effect. The further above 1 that the odds ratio is, the greater the increase in likelihood of using at least one substance. The further below 1, the greater the decrease in the likelihood of using at least one substance. A value of 1 for the odds ratio means that a factor has no effect.

Table C.1: Logistic regression model of any versus no substance use among S4 pupils 2010 and 2013: selected variables shown.

Beta S.E. of Beta Sig. Exp(B)
Gender of respondent Male .00
Female -0.17 0.04 .00 .84
SIMD quintiles 1 - Most deprived quintile .01
2 0.10 0.05 .05 1.10
3 0.18 0.05 .00 1.20
4 0.16 0.05 .00 1.17
5 - Least deprived quintile 0.18 0.05 .00 1.20
Urban rural classification based on home postcode Large urban areas .02
Other urban areas -0.06 0.04 .09 .94
Small accessible towns 0.03 0.06 .62 1.03
Small remote towns 0.10 0.08 .20 1.10
Accessible rural 0.02 0.05 .67 1.02
Remote rural 0.16 0.07 .01 1.17
Overall WEMWBS score banded into three categories Below average mental wellbeing .02
Average mental wellbeing -0.11 0.04 .01 .90
Above average mental wellbeing -0.04 0.07 .53 .96
Banded Strengths and Difficulties (SDQ) score Normal .00
Borderline 0.25 0.04 .00 1.28
Abnormal 0.34 0.05 .00 1.40
Actively taken part in youth groups No .06
Yes -0.09 0.04 .04 .91
Actively taken part in a drama, arts, music or singing groups No .10
Yes -0.08 0.05 .10 .92
Actively taken part in none of these No .00
Yes 0.17 0.06 .00 1.19
Frequency of seeing your friends At least weekly .08
Less than weekly -0.16 0.08 .03 .85
Frequency of listening to music At least weekly .00
Less than weekly -0.32 0.09 .00 .73
Frequency of watching sports matches At least weekly .06
Less than weekly -0.09 0.04 .03 .92
Frequency of going to the cinema At least weekly .00
Less than weekly 0.24 0.04 .00 1.27
Frequency of hanging around the street At least weekly .00
Less than weekly -0.61 0.03 .00 .54
Frequency of doing a hobby At least weekly .00
Less than weekly 0.22 0.03 .00 1.25
Frequency of going to a friend's house At least weekly .00
Less than weekly -0.48 0.05 .00 .62
Frequency of going to concerts or gigs At least weekly .00
Less than weekly -0.46 0.05 .00 .63
Frequency of going to church At least weekly .37
Less than weekly 0.07 0.06 .24 1.07
Frequency of doing sports At least weekly .01
Less than weekly 0.12 0.04 .00 1.13
Frequency of doing voluntary work At least weekly .06
Less than weekly 0.11 0.05 .02 1.12
Frequency of using social networking sites At least weekly .01
Less than weekly -0.30 0.10 .00 .74
Family status Single parent .00
Step parent (and one parent) 0.10 0.05 .06 1.10
Both parents -0.19 0.04 .00 .83
Other 0.15 0.08 .07 1.16
Paternal knowledge of activities - banded Below median .00
Median -0.20 0.05 .00 .82
Above median -0.14 0.04 .00 .87
Maternal knowledge of activities - banded Below median .00
Median -0.27 0.04 .00 .76
Above median -0.48 0.04 .00 .62
How well off would you say your family is? Very well off .00
Quite well off -0.11 0.05 .05 .90
Average -0.22 0.05 .00 .80
Not well off -0.32 0.08 .00 .73
Not at all well off 0.34 0.14 .01 1.41
Number of close friends None .00
One -0.59 0.16 .00 .55
Two or more -0.33 0.13 .01 .72
Are your friends older, younger, or about the same age as you? Older than me .00
Younger than me -0.44 0.14 .00 .64
About the same age as me -0.77 0.07 .00 .47
Mixed ages -0.29 0.07 .00 .75
Don't know 0.26 0.24 .28 1.30
How many evenings spend with friends 0-1 evenings .00
2-3 evenings 0.34 0.07 .00 1.40
4-5 evenings 0.64 0.07 .00 1.90
6-7 evenings 1.03 0.07 .00 2.80
How much do you like school at the moment? I like it a lot .00
I like it a bit -0.05 0.06 .38 .95
I don't like it very much 0.09 0.06 .13 1.10
I don't like it at all 0.23 0.07 .00 1.26
How often feel strained or pressured by the schoolwork Never .00
Sometimes -0.19 0.06 .00 .83
A lot of the time 0.00 0.06 .97 1.00
Truanting None .00
1-3 times 0.65 0.04 .00 1.91
4-10 times 1.13 0.05 .00 3.08
More than 10 times 1.39 0.06 .00 4.03
Ever excluded No .00
Yes 0.77 0.05 .00 2.16
Aspirations University .00
FE College 0.05 0.04 .20 1.05
Apprenticeship 0.29 0.06 .00 1.33
Working 0.06 0.05 .25 1.07
Other -0.07 0.05 .16 .93
Constant -0.39 0.25 .12 .68

Table C.2: Logistic regression model of individual substance use versus not use among S4 pupils 2010 and 2013: selected variables shown.

Drinking Smoking Drugs
Beta S.E. of Beta Sig. Exp(B) Beta S.E. of Beta Sig. Exp(B) Beta S.E. of Beta Sig. Exp(B)
Gender of respondent Male .26 .06 .00
Female -0.03 0.04 .57 0.98 0.12 0.05 .02 1.13 -0.59 0.05 .00 0.56
SIMD quintiles 1 - Most deprived quintile .00 .06 .02
2 0.09 0.05 .10 1.09 -0.04 0.06 .51 0.96 0.05 0.06 .44 1.05
3 0.23 0.06 .00 1.26 -0.05 0.07 .49 0.95 0.16 0.07 .02 1.17
4 0.19 0.06 .00 1.21 0.00 0.07 .94 1.00 0.06 0.07 .36 1.06
5 - Least deprived quintile 0.21 0.06 .00 1.24 0.14 0.07 .04 1.16 0.20 0.07 .00 1.22
Urban rural classification based on home postcode Large urban areas .00 .02 .00
Other urban areas -0.04 0.04 .35 0.96 0.06 0.05 .25 1.06 -0.09 0.05 .06 0.91
Small accessible towns 0.10 0.06 .09 1.11 0.10 0.08 .21 1.10 -0.22 0.08 .00 0.80
Small remote towns 0.18 0.08 .02 1.20 0.19 0.10 .06 1.21 -0.27 0.10 .01 0.76
Accessible rural 0.04 0.05 .45 1.04 0.18 0.07 .01 1.19 -0.23 0.07 .00 0.80
Remote rural 0.28 0.07 .00 1.32 0.30 0.09 .00 1.34 -0.22 0.09 .01 0.80
Entitled to Free School Meals Yes .01 .11 .00
No 0.06 0.05 .21 1.06 -0.11 0.05 .05 0.90 -0.30 0.05 .00 0.74
Overall WEMWBS score banded into three categories Below average mental wellbeing 0.16 0.07 .02 1.17 0.02 0.09 .82 1.02 -0.16 0.08 .05 0.85
Average mental wellbeing .00 .00 .00
Above average mental wellbeing 0.23 0.05 .00 1.26 0.17 0.06 .00 1.19 0.21 0.06 .00 1.23
Banded Strengths and Difficulties (SDQ) score Normal 0.24 0.05 .00 1.27 0.37 0.06 .00 1.45 0.16 0.06 .01 1.18
Borderline 0.00 0.00 .00 0.00 0.00 0.00 .69 0.00 0.00 0.00 .14 0.00
Abnormal -0.14 0.05 .00 0.87 0.03 0.06 .67 1.03 -0.11 0.06 .07 0.90
Actively taken part in youth groups No .35 .93 .85
Yes -0.05 0.05 .35 0.95 -0.01 0.07 .93 0.99 0.01 0.07 .85 1.01
Actively taken part in a drama, arts, music or singing groups No .00 .04 .04
Yes 0.19 0.07 .00 1.21 0.16 0.08 .04 1.18 0.16 0.08 .04 1.17
Actively taken part in none of these No .18 .01 .00
Yes -0.16 0.09 .07 0.85 -0.27 0.12 .02 0.77 -0.32 0.11 .00 0.73
Frequency of seeing your friends At least weekly .01 .29 .06
Less than weekly -0.28 0.10 .01 0.76 -0.13 0.13 .31 0.87 -0.21 0.13 .09 0.81
Frequency of listening to music At least weekly .00 .15 .20
Less than weekly -0.23 0.04 .00 0.80 0.03 0.06 .60 1.03 0.09 0.05 .08 1.09
Frequency of watching sports matches At least weekly .00 .00 .00
Less than weekly 0.17 0.04 .00 1.18 0.41 0.05 .00 1.51 0.33 0.05 .00 1.39
Frequency of going to the cinema At least weekly .00 .00 .00
Less than weekly -0.50 0.04 .00 0.61 -0.75 0.05 .00 0.47 -0.71 0.05 .00 0.49
Frequency of hanging around the street At least weekly .00 .00 .02
Less than weekly 0.30 0.04 .00 1.34 0.18 0.05 .00 1.20 0.02 0.05 .60 1.02
Frequency of doing a hobby At least weekly .00 .00 .00
Less than weekly -0.35 0.06 .00 0.70 -0.51 0.08 .00 0.60 -0.47 0.07 .00 0.62
Frequency of going to a friend's house At least weekly .00 .00 .00
Less than weekly -0.44 0.05 .00 0.64 -0.35 0.07 .00 0.70 -0.43 0.06 .00 0.65
Frequency of going to concerts or gigs At least weekly .01 .03 .00
Less than weekly 0.19 0.06 .00 1.21 0.08 0.08 .34 1.08 -0.24 0.07 .00 0.79
Frequency of going to church At least weekly .17 .00 .01
Less than weekly 0.08 0.04 .07 1.08 0.45 0.06 .00 1.57 0.14 0.05 .01 1.15
Frequency of doing sports At least weekly .30 .04 .05
Less than weekly 0.08 0.05 .12 1.09 0.16 0.07 .02 1.18 0.16 0.07 .02 1.18
Frequency of doing voluntary work At least weekly .14 .71 .31
Less than weekly -0.24 0.12 .05 0.79 -0.09 0.15 .52 0.91 -0.20 0.13 .13 0.82
Frequency of using social networking sites At least weekly .00 .00 .00
Less than weekly 0.12 0.06 .04 1.12 0.05 0.07 .48 1.05 0.03 0.07 .62 1.03
Family status Single parent -0.11 0.04 .01 0.89 -0.33 0.05 .00 0.72 -0.20 0.05 .00 0.82
Step parent (and one parent) 0.16 0.08 .07 1.17 0.22 0.09 .02 1.25 0.42 0.09 .00 1.52
Both parents .01 .05 .00
Other -0.19 0.06 .00 0.83 -0.21 0.08 .01 0.81 -0.24 0.07 .00 0.79
Paternal knowledge of activities - banded Below median -0.09 0.04 .05 0.92 -0.06 0.06 .27 0.94 -0.17 0.06 .00 0.85
Median .00 .00 .00
Above median -0.24 0.05 .00 0.79 -0.23 0.06 .00 0.79 -0.34 0.06 .00 0.71
Maternal knowledge of activities - banded Below median -0.34 0.04 .00 0.71 -0.38 0.06 .00 0.68 -0.60 0.06 .00 0.55
Median .00 .00 .16
Above median -0.13 0.06 .02 0.88 -0.12 0.07 .09 0.88 -0.12 0.07 .07 0.88
How well off would you say your family is? Very well off -0.32 0.06 .00 0.73 -0.17 0.07 .01 0.84 -0.17 0.07 .01 0.84
Quite well off -0.37 0.09 .00 0.69 -0.21 0.11 .05 0.81 -0.17 0.10 .10 0.84
Average 0.38 0.13 .00 1.47 0.13 0.16 .41 1.14 -0.06 0.16 .70 0.94
Not well off .00 .28 .00
Not at all well off -0.75 0.17 .00 0.47 -0.10 0.20 .63 0.91 -0.59 0.19 .00 0.55
Number of close friends None -0.31 0.14 .02 0.73 -0.25 0.16 .13 0.78 -0.50 0.15 .00 0.60
One .00 .00 .00
Two or more -0.26 0.15 .08 0.77 -0.79 0.19 .00 0.45 -0.44 0.18 .01 0.64
Are your friends older, younger, or about the same age as you? Older than me -0.66 0.07 .00 0.52 -0.83 0.08 .00 0.44 -0.79 0.08 .00 0.45
Younger than me -0.19 0.07 .01 0.82 -0.35 0.08 .00 0.70 -0.36 0.08 .00 0.70
About the same age as me -0.02 0.24 .94 0.98 -0.53 0.28 .06 0.59 0.38 0.27 .16 1.46
Mixed ages .00 .00 .00
Don't know 0.44 0.08 .00 1.55 0.28 0.11 .01 1.32 0.21 0.10 .03 1.23
How many evenings spend with friends 0-1 evenings 0.73 0.08 .00 2.07 0.80 0.11 .00 2.23 0.56 0.10 .00 1.75
2-3 evenings 0.93 0.08 .00 2.53 1.42 0.11 .00 4.15 0.82 0.10 .00 2.27
4-5 evenings .00 .03 .08
6-7 evenings 0.01 0.06 .91 1.01 -0.06 0.09 .52 0.95 -0.03 0.08 .72 0.97
How much do you like school at the moment? I like it a lot 0.17 0.07 .01 1.19 0.07 0.09 .41 1.08 0.03 0.08 .70 1.03
I like it a bit 0.34 0.07 .00 1.40 0.13 0.10 .17 1.14 0.14 0.09 .12 1.15
I don't like it very much .00 .02 .00
I don't like it at all -0.17 0.06 .00 0.84 -0.06 0.08 .41 0.94 -0.16 0.07 .02 0.85
How often feel strained or pressured by the schoolwork Never 0.05 0.06 .39 1.06 0.09 0.08 .27 1.09 0.06 0.08 .47 1.06
Sometimes .00 .00 .00
A lot of the time 0.55 0.04 .00 1.73 0.63 0.05 .00 1.88 0.67 0.05 .00 1.96
Truanting None 0.98 0.05 .00 2.66 1.25 0.06 .00 3.47 1.14 0.06 .00 3.12
1-3 times 1.14 0.06 .00 3.13 1.45 0.07 .00 4.28 1.49 0.07 .00 4.43
4-10 times .00 .00 .00
More than 10 times 0.50 0.05 .00 1.64 0.96 0.05 .00 2.60 0.87 0.05 .00 2.38
Ever excluded No .00 .00 .00
Yes -0.01 0.04 .75 0.99 0.43 0.06 .00 1.54 -0.06 0.05 .26 0.94
Aspirations University 0.25 0.06 .00 1.28 0.63 0.08 .00 1.87 0.12 0.07 .10 1.13
Further Education -0.04 0.06 .46 0.96 0.45 0.07 .00 1.57 -0.24 0.07 .00 0.78
Apprenticeship 0.01 0.05 .90 1.01 0.37 0.07 .00 1.45 -0.07 0.07 .26 0.93
Working -1.35 0.26 .00 0.26 -2.54 0.31 .00 0.08 -1.11 0.30 .00 0.33
Other .26 .06 .00
  Constant -0.03 0.04 .57 0.98 0.12 0.05 .02 1.13 -0.59 0.05 .00 0.56

Table C.3: Logistic regression model of multiple substance use versus single substance use among S4 pupils in 2010 and 2013 who used at least one substance: selected variables shown.

Beta S.E. of Beta Sig. Exp(B)
Gender of respondent Male .00 .00
Female -0.23 0.07 .00 .79
SIMD quintiles 1 - Most deprived quintile .08 .00
2 -0.01 0.08 .86 .99
3 0.00 0.09 1.00 1.00
4 -0.06 0.09 .52 .95
5 - Least deprived quintile 0.18 0.09 .04 1.20
Urban rural classification based on home postcode Large urban areas .39 .00
Other urban areas 0.07 0.06 .30 1.07
Small accessible towns 0.07 0.09 .46 1.07
Small remote towns 0.02 0.12 .88 1.02
Accessible rural -0.07 0.09 .38 .93
Remote rural 0.19 0.11 .09 1.20
Overall WEMWBS score banded into three categories Below average mental wellbeing .61 .00
Average mental wellbeing -0.07 0.07 .30 .93
Above average mental wellbeing 0.02 0.11 .87 1.02
Banded Strengths and Difficulties (SDQ) score Normal .17 .00
Borderline 0.14 0.07 .04 1.16
Abnormal 0.08 0.08 .28 1.09
Actively taken part in youth groups No .45 .00
Yes -0.03 0.08 .70 .97
Actively taken part in a drama, arts, music or singing groups No .31 .00
Yes 0.09 0.09 .31 1.09
Actively taken part in none of these No .02 .00
Yes 0.22 0.10 .02 1.25
Frequency of seeing your friends At least weekly .01 .00
Less than weekly -0.42 0.16 .01 .65
Frequency of listening to music At least weekly .34 .00
Less than weekly -0.26 0.19 .17 .77
Frequency of watching sports matches At least weekly .45 .00
Less than weekly 0.08 0.07 .22 1.08
Frequency of going to the cinema At least weekly .00 .00
Less than weekly 0.27 0.06 .00 1.32
Frequency of hanging around the street At least weekly .00 .00
Less than weekly -0.43 0.06 .00 .65
Frequency of doing a hobby At least weekly .89 .00
Less than weekly 0.03 0.06 .64 1.03
Frequency of going to a friend's house At least weekly .24 .00
Less than weekly -0.16 0.10 .09 .85
Frequency of going to concerts or gigs At least weekly .00 .00
Less than weekly -0.28 0.08 .00 .76
Frequency of going to church At least weekly .12 .00
Less than weekly -0.08 0.11 .47 .93
Frequency of doing sports At least weekly .00 .00
Less than weekly 0.31 0.07 .00 1.36
Frequency of doing voluntary work At least weekly .23 .00
Less than weekly 0.06 0.09 .47 1.07
Frequency of using social networking sites At least weekly .35 .00
Less than weekly 0.28 0.20 .16 1.33
Family status Single parent .00 .00
Step parent (and one parent) 0.01 0.08 .93 1.01
Both parents -0.11 0.06 .09 .90
Other 0.49 0.13 .00 1.63
Paternal knowledge of activities - banded Below median .03 .00
Median -0.21 0.10 .03 .81
Above median -0.11 0.07 .11 .89
Maternal knowledge of activities - banded Below median .00 .00
Median -0.16 0.08 .04 .86
Above median -0.28 0.07 .00 .76
How well off would you say family is? Very well off .02 .00
Quite well off -0.26 0.09 .00 .77
Average -0.29 0.09 .00 .75
Not well off -0.15 0.13 .27 .86
Not at all well off -0.30 0.19 .11 .74
Number of close friends None 0.00 0.00 .27 .00
One -0.13 0.25 .62 .88
Two or more -0.16 0.20 .43 .85
Are your friends older, younger, or about the same age as you? Older than me .00 .00
Younger than me -0.12 0.24 .61 .89
About the same age as me -0.50 0.10 .00 .61
Mixed ages -0.19 0.10 .05 .83
Don't know -0.16 0.35 .65 .85
How many evenings spend with friends 0-1 evenings .00 .00
2-3 evenings 0.20 0.14 .17 1.22
4-5 evenings 0.65 0.14 .00 1.91
6-7 evenings 0.85 0.15 .00 2.35
How much do you like school at the moment? I like it a lot .05 .00
I like it a bit 0.04 0.11 .69 1.04
I don't like it very much 0.08 0.11 .50 1.08
I don't like it at all 0.25 0.12 .03 1.29
How often feel strained or pressured by the schoolwork Never .12 .00
Sometimes -0.05 0.09 .56 .95
A lot of the time 0.09 0.10 .37 1.09
Beta S.E. of Beta Sig. Exp(B)
Truanting None .00 .00
1-3 times 0.30 0.07 .00 1.35
4-10 times 0.74 0.08 .00 2.10
More than 10 times 1.08 0.09 .00 2.95
Ever excluded No .00 .00
Yes 0.56 0.07 .00 1.75
Aspirations University .00 .00
Further Education 0.15 0.07 .03 1.16
Apprenticeships 0.25 0.09 .01 1.29
Working -0.11 0.09 .22 .90
Other 0.22 0.09 .01 1.25
Constant -1.06 0.39 .01 .35

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